Java/Database SQL JDBC/Column

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Версия от 18:01, 31 мая 2010; (обсуждение)
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Adding a New Column Name in Database Table

  
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
public class Main {
  public static void main(String[] argv) throws Exception {
    Class.forName("com.mysql.jdbc.Driver");
    Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbctutorial",
        "root", "root");
    Statement st = con.createStatement();
    int n = st.executeUpdate("ALTER TABLE mytable ADD col int");
    System.out.println("Query OK, " + n + " rows affected");
  }
}





Arrange a Column of Database Table

  
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class Main {
  public static void main(String[] argv) throws Exception {
    Class.forName("com.mysql.jdbc.Driver");
    Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbctutorial",
        "root", "root");
    Statement st = con.createStatement();
    ResultSet res = st.executeQuery("SELECT col_name  FROM mytable  ORDER BY col_name ASC");
    while (res.next()) {
      int col = res.getInt(1);
      System.out.println(col);
    }
  }
}





Change Column Name of a Table

  
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
public class Main {
  public static void main(String[] argv) throws Exception {
    Class.forName("com.mysql.jdbc.Driver");
    Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbctutorial",
        "root", "root");
    Statement st = con.createStatement();
    int n = st.executeUpdate("ALTER TABLE myTable CHANGE old_col  new_col int");
    System.out.println("Query OK, " + n + " rows affected");
  }
}





Delete a Column from a Database Table

  
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
public class Main {
  public static void main(String[] argv) throws Exception {
    Class.forName("com.mysql.jdbc.Driver");
    Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbctutorial",
        "root", "root");
    Statement st = con.createStatement();
    st.executeUpdate("ALTER TABLE mytable DROP col");
    System.out.println("Column is deleted successfully!");
  }
}





Designated column"s table name

  
 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  private static final String DRIVER = "com.mysql.jdbc.Driver";
  private static final String URL = "jdbc:mysql://localhost/testdb";
  private static final String USERNAME = "root";
  private static final String PASSWORD = "";
  public static void main(String[] args) throws Exception {
    Class.forName(DRIVER);
    Connection connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
    Statement statement = connection.createStatement();
    String query = "SELECT a.id, a.username, a.country_id, b.country_name " + "FROM users a "
        + "LEFT JOIN countries b ON a.country_id = b.id";
    ResultSet resultSet = statement.executeQuery(query);
    ResultSetMetaData metadata = resultSet.getMetaData();
    String tableName = metadata.getTableName(1);
    System.out.println("Table name of column "id" = " + tableName);
    tableName = metadata.getTableName(4);
    System.out.println("Table name of column "country name" = " + tableName);
  }
}





Get Column Corresponding Class Name

 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    st = conn.createStatement();
    ResultSet rs = st.executeQuery("SELECT * FROM survey");
    ResultSetMetaData rsMetaData = rs.getMetaData();
    int numberOfColumns = rsMetaData.getColumnCount();
    System.out.println("resultSet MetaData column Count=" + numberOfColumns);
    for (int i = 1; i <= numberOfColumns; i++) {
      System.out.println("column MetaData ");
      System.out.println("column number " + i);

      // get the designated column"s class name.
      System.out.println(rsMetaData.getColumnClassName(i));
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Get Column Detail Information

 
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    ResultSet rsColumns = null;
    DatabaseMetaData meta = conn.getMetaData();
    rsColumns = meta.getColumns(null, "%", "code", "%");
    
    while (rsColumns.next()) {
      String columnType = rsColumns.getString("TYPE_NAME");
      String columnName = rsColumns.getString("COLUMN_NAME");
      int size = rsColumns.getInt("COLUMN_SIZE");
      int nullable = rsColumns.getInt("NULLABLE");
      int position = rsColumns.getInt("ORDINAL_POSITION");
      System.out.println("column name=" + columnName);
      System.out.println("type=" + columnType);
      System.out.println("size=" + size);
      if (nullable == DatabaseMetaData.columnNullable) {
        System.out.println("nullable is true");
      } else {
        System.out.println("nullable is false");
      }
      System.out.println("position" + position);
    }
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver); 
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Get Column Display Size.zip

 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    st = conn.createStatement();
    ResultSet rs = st.executeQuery("SELECT * FROM survey");
    ResultSetMetaData rsMetaData = rs.getMetaData();
    int numberOfColumns = rsMetaData.getColumnCount();
    System.out.println("resultSet MetaData column Count=" + numberOfColumns);
    for (int i = 1; i <= numberOfColumns; i++) {
      System.out.println("column MetaData ");
      System.out.println("column number " + i);
      // indicates the designated column"s normal maximum width in
      // characters
      System.out.println(rsMetaData.getColumnDisplaySize(i));
      // gets the designated column"s suggested title
      // for use in printouts and displays.
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Get Column Label

 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    st = conn.createStatement();
    ResultSet rs = st.executeQuery("SELECT * FROM survey");
    ResultSetMetaData rsMetaData = rs.getMetaData();
    int numberOfColumns = rsMetaData.getColumnCount();
    System.out.println("resultSet MetaData column Count=" + numberOfColumns);
    for (int i = 1; i <= numberOfColumns; i++) {
      System.out.println("column MetaData ");
      System.out.println("column number " + i);
      // get the designated column"s name.
      System.out.println(rsMetaData.getColumnLabel(i));
      
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Get Column Name

 
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    ResultSet rsColumns = null;
    DatabaseMetaData meta = conn.getMetaData();
    rsColumns = meta.getColumns(null, null, "survey", null);
    while (rsColumns.next()) {
      String columnName = rsColumns.getString("COLUMN_NAME");
      System.out.println("column name=" + columnName);
      String columnType = rsColumns.getString("TYPE_NAME");
      System.out.println("type:" + columnType);
      int size = rsColumns.getInt("COLUMN_SIZE");
      System.out.println("size:" + size);
      int nullable = rsColumns.getInt("NULLABLE");
      if (nullable == DatabaseMetaData.columnNullable) {
        System.out.println("nullable true");
      } else {
        System.out.println("nullable false");
      }
      int position = rsColumns.getInt("ORDINAL_POSITION");
      System.out.println("position:" + position);
      
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Get Column Name And Type For A Table

 
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    ResultSet rsColumns = null;
    DatabaseMetaData meta = conn.getMetaData();
    rsColumns = meta.getColumns(null, null, "survey", null);
    while (rsColumns.next()) {
      System.out.println(rsColumns.getString("TYPE_NAME"));
      System.out.println(rsColumns.getString("COLUMN_NAME"));
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Get Column Name From ResultSet Metadata

 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    st = conn.createStatement();
    ResultSet rs = st.executeQuery("SELECT * FROM survey");
    ResultSetMetaData rsMetaData = rs.getMetaData();
    int numberOfColumns = rsMetaData.getColumnCount();
    System.out.println("resultSet MetaData column Count=" + numberOfColumns);
    for (int i = 1; i <= numberOfColumns; i++) {
      System.out.println("column MetaData ");
      System.out.println("column number " + i);
      // get the column"s name.
      System.out.println(rsMetaData.getColumnName(i));

      
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Get Column Names From ResultSet for MySQL

 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
public class GetColumnNamesFromResultSet_MySQL {
  public static Connection getConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/databaseName";
    String username = "root";
    String password = "root";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static void getColumnNames(ResultSet rs) throws SQLException {
    if (rs == null) {
      return;
    }
    ResultSetMetaData rsMetaData = rs.getMetaData();
    int numberOfColumns = rsMetaData.getColumnCount();
    // get the column names; column indexes start from 1
    for (int i = 1; i < numberOfColumns + 1; i++) {
      String columnName = rsMetaData.getColumnName(i);
      // Get the name of the column"s table name
      String tableName = rsMetaData.getTableName(i);
      System.out.println("column name=" + columnName + " table=" + tableName + "");
    }
  }
  public static void main(String[] args) {
    Connection conn = null;
    Statement stmt = null;
    ResultSet rs = null;
    try {
      conn = getConnection();
      // prepare query
      String query = "select id, name, age from employees";
      // create a statement
      stmt = conn.createStatement();
      // execute query and return result as a ResultSet
      rs = stmt.executeQuery(query);
      // get the column names from the ResultSet
      getColumnNames(rs);
    } catch (Exception e) {
      e.printStackTrace();
      System.exit(1);
    } finally {
      // release database resources
      try {
        rs.close();
        stmt.close();
        conn.close();
      } catch (SQLException e) {
        e.printStackTrace();
      }
    }
  }
}





Get Column Number Of Digits To Right Of The Decimal Point

 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    st = conn.createStatement();
    ResultSet rs = st.executeQuery("SELECT * FROM survey");
    ResultSetMetaData rsMetaData = rs.getMetaData();
    int numberOfColumns = rsMetaData.getColumnCount();
    System.out.println("resultSet MetaData column Count=" + numberOfColumns);
    for (int i = 1; i <= numberOfColumns; i++) {
      System.out.println("column MetaData ");
      System.out.println("column number " + i);

      // gets the designated column"s number of
      // digits to right of the decimal point.
      System.out.println(rsMetaData.getScale(i));
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Get Column Number Of Presions Number Of Decimal Digits

 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    st = conn.createStatement();
    ResultSet rs = st.executeQuery("SELECT * FROM survey");
    ResultSetMetaData rsMetaData = rs.getMetaData();
    int numberOfColumns = rsMetaData.getColumnCount();
    System.out.println("resultSet MetaData column Count=" + numberOfColumns);
    for (int i = 1; i <= numberOfColumns; i++) {
      System.out.println("column MetaData ");
      System.out.println("column number " + i);

      // get the designated column"s number of decimal digits.
      System.out.println(rsMetaData.getPrecision(i));
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Get Column ORDINAL POSITION

 
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    ResultSet rsColumns = null;
    DatabaseMetaData meta = conn.getMetaData();
    rsColumns = meta.getColumns(null, null, "survey", null);
    while (rsColumns.next()) {
      String columnName = rsColumns.getString("COLUMN_NAME");
      System.out.println("column name=" + columnName);
      String columnType = rsColumns.getString("TYPE_NAME");
      System.out.println("type:" + columnType);
      int size = rsColumns.getInt("COLUMN_SIZE");
      System.out.println("size:" + size);
      int nullable = rsColumns.getInt("NULLABLE");
      if (nullable == DatabaseMetaData.columnNullable) {
        System.out.println("nullable true");
      } else {
        System.out.println("nullable false");
      }
      int position = rsColumns.getInt("ORDINAL_POSITION");
      System.out.println("position:" + position);
      
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Get Column Privileges

 
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
//    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    ResultSet privileges = null;
    DatabaseMetaData meta = conn.getMetaData();
    // The "_" character represents any single character.
    // The "%" character represents any sequence of zero
    // or more characters.
    privileges = meta.getColumnPrivileges(conn.getCatalog(),null,"survey","%");
    while (privileges.next()) {
      String catalog = privileges.getString("TABLE_CAT");
      String schema = privileges.getString("TABLE_SCHEM");
      String tableName = privileges.getString("TABLE_NAME");
      String dbColumn = privileges.getString("COLUMN_NAME");
      String privilege = privileges.getString("PRIVILEGE");
      String grantor = privileges.getString("GRANTOR");
      String grantee = privileges.getString("GRANTEE");
      String isGrantable = privileges.getString("IS_GRANTABLE");
      System.out.println("table name:" + tableName);
      System.out.println("catalog:"+catalog);
      System.out.println("column:"+dbColumn);
      System.out.println("schema:"+ schema);
      System.out.println("privilege:"+privilege);
      System.out.println("grantor:"+grantor);
      System.out.println("isGrantable:"+isGrantable);
      System.out.println("grantee:"+grantee);
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Get Column Size

 
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    ResultSet rsColumns = null;
    DatabaseMetaData meta = conn.getMetaData();
    rsColumns = meta.getColumns(null, null, "survey", null);
    while (rsColumns.next()) {
      String columnName = rsColumns.getString("COLUMN_NAME");
      System.out.println("column name=" + columnName);
      String columnType = rsColumns.getString("TYPE_NAME");
      System.out.println("type:" + columnType);
      int size = rsColumns.getInt("COLUMN_SIZE");
      System.out.println("size:" + size);
      int nullable = rsColumns.getInt("NULLABLE");
      if (nullable == DatabaseMetaData.columnNullable) {
        System.out.println("nullable true");
      } else {
        System.out.println("nullable false");
      }
      int position = rsColumns.getInt("ORDINAL_POSITION");
      System.out.println("position:" + position);
      
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Get Column Sql Data Type

 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    st = conn.createStatement();
    ResultSet rs = st.executeQuery("SELECT * FROM survey");
    ResultSetMetaData rsMetaData = rs.getMetaData();
    int numberOfColumns = rsMetaData.getColumnCount();
    System.out.println("resultSet MetaData column Count=" + numberOfColumns);
    for (int i = 1; i <= numberOfColumns; i++) {
      System.out.println("column MetaData ");
      System.out.println("column number " + i);
      // get the designated column"s SQL type.
      System.out.println(rsMetaData.getColumnType(i));
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Get Column SQL Type Name

 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    st = conn.createStatement();
    ResultSet rs = st.executeQuery("SELECT * FROM survey");
    ResultSetMetaData rsMetaData = rs.getMetaData();
    int numberOfColumns = rsMetaData.getColumnCount();
    System.out.println("resultSet MetaData column Count=" + numberOfColumns);
    for (int i = 1; i <= numberOfColumns; i++) {
      System.out.println("column MetaData ");
      System.out.println("column number " + i);

      // get the designated column"s SQL type name.
      System.out.println(rsMetaData.getColumnTypeName(i));
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Get Column Type

 
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    ResultSet rsColumns = null;
    DatabaseMetaData meta = conn.getMetaData();
    rsColumns = meta.getColumns(null, null, "survey", null);
    while (rsColumns.next()) {
      String columnName = rsColumns.getString("COLUMN_NAME");
      System.out.println("column name=" + columnName);
      String columnType = rsColumns.getString("TYPE_NAME");
      System.out.println("type:" + columnType);
      int size = rsColumns.getInt("COLUMN_SIZE");
      System.out.println("size:" + size);
      int nullable = rsColumns.getInt("NULLABLE");
      if (nullable == DatabaseMetaData.columnNullable) {
        System.out.println("nullable true");
      } else {
        System.out.println("nullable false");
      }
      int position = rsColumns.getInt("ORDINAL_POSITION");
      System.out.println("position:" + position);
      
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Get Table Optimal Set Of Columns

 
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    DatabaseMetaData meta = conn.getMetaData();
    // The "_" character represents any single character.
    // The "%" character represents any sequence of zero
    // or more characters.
    ResultSet rs = meta.getBestRowIdentifier(conn.getCatalog(), null, "survey",
        DatabaseMetaData.bestRowTemporary, false);
    while (rs.next()) {
      short actualScope = rs.getShort("SCOPE");
      String columnName = rs.getString("COLUMN_NAME");
      int dataType = rs.getInt("DATA_TYPE");
      String typeName = rs.getString("TYPE_NAME");
      int columnSize = rs.getInt("COLUMN_SIZE");
      short decimalDigits = rs.getShort("DECIMAL_DIGITS");
      short pseudoColumn = rs.getShort("PSEUDO_COLUMN");
      System.out.println("tableName=survey");
      System.out.println("scope=" + actualScope);
      System.out.println("columnName=" + columnName);
      System.out.println("dataType=" + dataType);
      System.out.println("typeName" + typeName);
      System.out.println("columnSize" + columnSize);
      System.out.println("decimalDigits" + decimalDigits);
      System.out.println("pseudoColumn" + pseudoColumn);
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





If a table column can have a null value or not?

  
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  private static final String DRIVER = "com.mysql.jdbc.Driver";
  private static final String URL = "jdbc:mysql://localhost/testdb";
  private static final String USERNAME = "root";
  private static final String PASSWORD = "";
  public static void main(String[] args) throws Exception {
    Class.forName(DRIVER);
    Connection connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
    Statement statement = connection.createStatement();
    ResultSet resultSet = statement.executeQuery("SELECT id, username FROM users");
    ResultSetMetaData metadata = resultSet.getMetaData();
    int nullability = metadata.isNullable(1);
    if (nullability == ResultSetMetaData.columnNullable) {
      System.out.println("Columns ID can have a null value");
    } else if (nullability == ResultSetMetaData.columnNoNulls) {
      System.out.println("Columns ID does not allowed to have a null value");
    } else if (nullability == ResultSetMetaData.columnNullableUnknown) {
      System.out.println("Nullability unknown");
    }
  }
}





If a table column value is auto-increment?

  
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  private static final String DRIVER = "com.mysql.jdbc.Driver";
  private static final String URL = "jdbc:mysql://localhost/testdb";
  private static final String USERNAME = "root";
  private static final String PASSWORD = "";
  public static void main(String[] args) throws Exception {
    Class.forName(DRIVER);
    Connection connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
    Statement statement = connection.createStatement();
    ResultSet resultSet = statement.executeQuery("SELECT id, username FROM users");
    ResultSetMetaData metadata = resultSet.getMetaData();
    if (metadata.isAutoIncrement(1)) {
      System.out.println("Column ID is an auto-increment column");
    }
  }
}





Is Column A Cash Value

 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    st = conn.createStatement();
    ResultSet rs = st.executeQuery("SELECT * FROM survey");
    ResultSetMetaData rsMetaData = rs.getMetaData();
    int numberOfColumns = rsMetaData.getColumnCount();
    System.out.println("resultSet MetaData column Count=" + numberOfColumns);
    for (int i = 1; i <= numberOfColumns; i++) {
      System.out.println("column MetaData ");
      System.out.println("column number " + i);

      // indicates whether the designated column is a cash value.
      System.out.println(rsMetaData.isCurrency(i));
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Is Column Auto Increase

 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    st = conn.createStatement();
    ResultSet rs = st.executeQuery("SELECT * FROM survey");
    ResultSetMetaData rsMetaData = rs.getMetaData();
    int numberOfColumns = rsMetaData.getColumnCount();
    System.out.println("resultSet MetaData column Count=" + numberOfColumns);
    for (int i = 1; i <= numberOfColumns; i++) {
      System.out.println("column MetaData ");
      System.out.println("column number " + i);

      // indicates whether the designated column is
      // automatically numbered, thus read-only.
      System.out.println(rsMetaData.isAutoIncrement(i));
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Is Column Case Sensitive

 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    st = conn.createStatement();
    ResultSet rs = st.executeQuery("SELECT * FROM survey");
    ResultSetMetaData rsMetaData = rs.getMetaData();
    int numberOfColumns = rsMetaData.getColumnCount();
    System.out.println("resultSet MetaData column Count=" + numberOfColumns);
    for (int i = 1; i <= numberOfColumns; i++) {
      System.out.println("column MetaData ");
      System.out.println("column number " + i);

      // Indicates whether a column"s case matters
      // in the designated column.
      System.out.println(rsMetaData.isCaseSensitive(i));
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Is Column Definitely Writable

 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    st = conn.createStatement();
    ResultSet rs = st.executeQuery("SELECT * FROM survey");
    ResultSetMetaData rsMetaData = rs.getMetaData();
    int numberOfColumns = rsMetaData.getColumnCount();
    System.out.println("resultSet MetaData column Count=" + numberOfColumns);
    for (int i = 1; i <= numberOfColumns; i++) {
      System.out.println("column MetaData ");
      System.out.println("column number " + i);
      // indicates whether a write on the designated
      // column will definitely succeed.
      System.out.println(rsMetaData.isDefinitelyWritable(i));
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Is Column Nullable

 
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    ResultSet rsColumns = null;
    DatabaseMetaData meta = conn.getMetaData();
    rsColumns = meta.getColumns(null, null, "survey", null);
    while (rsColumns.next()) {
      String columnName = rsColumns.getString("COLUMN_NAME");
      System.out.println("column name=" + columnName);
      String columnType = rsColumns.getString("TYPE_NAME");
      System.out.println("type:" + columnType);
      int size = rsColumns.getInt("COLUMN_SIZE");
      System.out.println("size:" + size);
      int nullable = rsColumns.getInt("NULLABLE");
      if (nullable == DatabaseMetaData.columnNullable) {
        System.out.println("nullable true");
      } else {
        System.out.println("nullable false");
      }
      int position = rsColumns.getInt("ORDINAL_POSITION");
      System.out.println("position:" + position);
      
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Is Column Nullable From ResultSet Metadata

 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    st = conn.createStatement();
    ResultSet rs = st.executeQuery("SELECT * FROM survey");
    ResultSetMetaData rsMetaData = rs.getMetaData();
    int numberOfColumns = rsMetaData.getColumnCount();
    System.out.println("resultSet MetaData column Count=" + numberOfColumns);
    for (int i = 1; i <= numberOfColumns; i++) {
      System.out.println("column MetaData ");
      System.out.println("column number " + i);
      // indicates the nullability of values
      // in the designated column.
      System.out.println(rsMetaData.isNullable(i));
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Is Column Readonly

 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    st = conn.createStatement();
    ResultSet rs = st.executeQuery("SELECT * FROM survey");
    ResultSetMetaData rsMetaData = rs.getMetaData();
    int numberOfColumns = rsMetaData.getColumnCount();
    System.out.println("resultSet MetaData column Count=" + numberOfColumns);
    for (int i = 1; i <= numberOfColumns; i++) {
      System.out.println("column MetaData ");
      System.out.println("column number " + i);

      // Indicates whether the designated column
      // is definitely not writable.
      System.out.println(rsMetaData.isReadOnly(i));
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Is Column Searchable

 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    st = conn.createStatement();
    ResultSet rs = st.executeQuery("SELECT * FROM survey");
    ResultSetMetaData rsMetaData = rs.getMetaData();
    int numberOfColumns = rsMetaData.getColumnCount();
    System.out.println("resultSet MetaData column Count=" + numberOfColumns);
    for (int i = 1; i <= numberOfColumns; i++) {
      System.out.println("column MetaData ");
      System.out.println("column number " + i);

      // Indicates whether a column"s case matters
      // in the designated column.
      System.out.println(rsMetaData.isSearchable(i));
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Is Column Signed Number

 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    st = conn.createStatement();
    ResultSet rs = st.executeQuery("SELECT * FROM survey");
    ResultSetMetaData rsMetaData = rs.getMetaData();
    int numberOfColumns = rsMetaData.getColumnCount();
    System.out.println("resultSet MetaData column Count=" + numberOfColumns);
    for (int i = 1; i <= numberOfColumns; i++) {
      System.out.println("column MetaData ");
      System.out.println("column number " + i);

      // indicates whether values in the designated
      // column are signed numbers.
      System.out.println(rsMetaData.isSigned(i));
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Is Column Writable

 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class Main {
  public static void main(String[] args) throws Exception {
    Connection conn = getMySqlConnection();
    System.out.println("Got Connection.");
    Statement st = conn.createStatement();
    st.executeUpdate("drop table survey;");
    st.executeUpdate("create table survey (id int,name varchar(30));");
    st.executeUpdate("insert into survey (id,name ) values (1,"nameValue")");
    st = conn.createStatement();
    ResultSet rs = st.executeQuery("SELECT * FROM survey");
    ResultSetMetaData rsMetaData = rs.getMetaData();
    int numberOfColumns = rsMetaData.getColumnCount();
    System.out.println("resultSet MetaData column Count=" + numberOfColumns);
    for (int i = 1; i <= numberOfColumns; i++) {
      System.out.println("column MetaData ");
      System.out.println("column number " + i);
      // indicates whether a write on the designated
      // column will succeed.
      System.out.println(rsMetaData.isWritable(i));
    }
    st.close();
    conn.close();
  }
  private static Connection getHSQLConnection() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    return DriverManager.getConnection(url, "sa", "");
  }
  public static Connection getMySqlConnection() throws Exception {
    String driver = "org.gjt.mm.mysql.Driver";
    String url = "jdbc:mysql://localhost/demo2s";
    String username = "oost";
    String password = "oost";
    Class.forName(driver);
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@localhost:1521:caspian";
    String username = "mp";
    String password = "mp2";
    Class.forName(driver); // load Oracle driver
    Connection conn = DriverManager.getConnection(url, username, password);
    return conn;
  }
}





Make Unique Column in Database Table

  
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
public class Main {
  public static void main(String[] argv) throws Exception {
    Class.forName("com.mysql.jdbc.Driver");
    Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbctutorial",
        "root", "root");
    Statement st = con.createStatement();
    int n = st.executeUpdate("ALTER TABLE mytable ADD UNIQUE( colName)");
    System.out.println("Query OK, " + n + " rows affected.");
  }
}





Remove Unique Column in Database Table

  
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
public class Main {
  public static void main(String[] argv) throws Exception {
    Class.forName("com.mysql.jdbc.Driver");
    Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbctutorial",
        "root", "root");
    Statement st = con.createStatement();
    int n = st.executeUpdate("ALTER TABLE mytable DROP INDEX col");
    System.out.println("Query OK, " + n + " rows affected.");
  }
}





Sum of Column in a Database Table

  
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class Main {
  public static void main(String[] argv) throws Exception {
    int sum = 0;
    Class.forName("com.mysql.jdbc.Driver");
    Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbctutorial",
        "root", "root");
    Statement st = con.createStatement();
    ResultSet res = st.executeQuery("SELECT SUM(col) FROM mytable");
    while (res.next()) {
      int c = res.getInt(1);
      sum = sum + c;
    }
    System.out.println("Sum of column = " + sum);
  }
}





Use DatabaseMetaData to get table column names

  
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.ResultSet;
public class Main {
  private static final String DRIVER = "com.mysql.jdbc.Driver";
  private static final String URL = "jdbc:mysql://localhost/testdb";
  private static final String USERNAME = "root";
  private static final String PASSWORD = "";
  public static void main(String[] args) throws Exception {
    Class.forName(DRIVER);
    Connection connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
    DatabaseMetaData metadata = connection.getMetaData();
    ResultSet resultSet = metadata.getColumns(null, null, "users", null);
    while (resultSet.next()) {
      String name = resultSet.getString("COLUMN_NAME");
      String type = resultSet.getString("TYPE_NAME");
      int size = resultSet.getInt("COLUMN_SIZE");
      System.out.println("Column name: [" + name + "]; type: [" + type + "]; size: [" + size + "]");
    }
    connection.close();
  }
}


Источник — «http://jexp.ru/index.php?title=Java/Database_SQL_JDBC/Column&oldid=6974»