Java/Database SQL JDBC/Column
Содержание
- 1 Adding a New Column Name in Database Table
- 2 Arrange a Column of Database Table
- 3 Change Column Name of a Table
- 4 Delete a Column from a Database Table
- 5 Designated column"s table name
- 6 Get Column Corresponding Class Name
- 7 Get Column Detail Information
- 8 Get Column Display Size.zip
- 9 Get Column Label
- 10 Get Column Name
- 11 Get Column Name And Type For A Table
- 12 Get Column Name From ResultSet Metadata
- 13 Get Column Names From ResultSet for MySQL
- 14 Get Column Number Of Digits To Right Of The Decimal Point
- 15 Get Column Number Of Presions Number Of Decimal Digits
- 16 Get Column ORDINAL POSITION
- 17 Get Column Privileges
- 18 Get Column Size
- 19 Get Column Sql Data Type
- 20 Get Column SQL Type Name
- 21 Get Column Type
- 22 Get Table Optimal Set Of Columns
- 23 If a table column can have a null value or not?
- 24 If a table column value is auto-increment?
- 25 Is Column A Cash Value
- 26 Is Column Auto Increase
- 27 Is Column Case Sensitive
- 28 Is Column Definitely Writable
- 29 Is Column Nullable
- 30 Is Column Nullable From ResultSet Metadata
- 31 Is Column Readonly
- 32 Is Column Searchable
- 33 Is Column Signed Number
- 34 Is Column Writable
- 35 Make Unique Column in Database Table
- 36 Remove Unique Column in Database Table
- 37 Sum of Column in a Database Table
- 38 Use DatabaseMetaData to get table column names
Adding a New Column Name in Database Table
<source lang="java">
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"); }
}
</source>
Arrange a Column of Database Table
<source lang="java">
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); } }
}
</source>
Change Column Name of a Table
<source lang="java">
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"); }
}
</source>
Delete a Column from a Database Table
<source lang="java">
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!"); }
}
</source>
Designated column"s table name
<source lang="java">
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); }
}
</source>
Get Column Corresponding Class Name
<source lang="java">
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; }
}
</source>
Get Column Detail Information
<source lang="java">
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; }
}
</source>
Get Column Display Size.zip
<source lang="java">
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; }
}
</source>
Get Column Label
<source lang="java">
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; }
}
</source>
Get Column Name
<source lang="java">
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; }
}
</source>
Get Column Name And Type For A Table
<source lang="java">
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; }
}
</source>
Get Column Name From ResultSet Metadata
<source lang="java">
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; }
}
</source>
Get Column Names From ResultSet for MySQL
<source lang="java">
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(); } } }
}
</source>
Get Column Number Of Digits To Right Of The Decimal Point
<source lang="java">
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; }
}
</source>
Get Column Number Of Presions Number Of Decimal Digits
<source lang="java">
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; }
}
</source>
Get Column ORDINAL POSITION
<source lang="java">
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; }
}
</source>
Get Column Privileges
<source lang="java">
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; }
}
</source>
Get Column Size
<source lang="java">
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; }
}
</source>
Get Column Sql Data Type
<source lang="java">
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; }
}
</source>
Get Column SQL Type Name
<source lang="java">
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; }
}
</source>
Get Column Type
<source lang="java">
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; }
}
</source>
Get Table Optimal Set Of Columns
<source lang="java">
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; }
}
</source>
If a table column can have a null value or not?
<source lang="java">
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"); } }
}
</source>
If a table column value is auto-increment?
<source lang="java">
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"); } }
}
</source>
Is Column A Cash Value
<source lang="java">
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; }
}
</source>
Is Column Auto Increase
<source lang="java">
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; }
}
</source>
Is Column Case Sensitive
<source lang="java">
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; }
}
</source>
Is Column Definitely Writable
<source lang="java">
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; }
}
</source>
Is Column Nullable
<source lang="java">
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; }
}
</source>
Is Column Nullable From ResultSet Metadata
<source lang="java">
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; }
}
</source>
Is Column Readonly
<source lang="java">
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; }
}
</source>
Is Column Searchable
<source lang="java">
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; }
}
</source>
Is Column Signed Number
<source lang="java">
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; }
}
</source>
Is Column Writable
<source lang="java">
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; }
}
</source>
Make Unique Column in Database Table
<source lang="java">
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."); }
}
</source>
Remove Unique Column in Database Table
<source lang="java">
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."); }
}
</source>
Sum of Column in a Database Table
<source lang="java">
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); }
}
</source>
Use DatabaseMetaData to get table column names
<source lang="java">
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(); }
}
</source>