Java Tutorial/Database/Data Truncation
Версия от 17:44, 31 мая 2010; (обсуждение)
Check Data Truncation
import java.sql.Connection;
import java.sql.DataTruncation;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLWarning;
import java.sql.Statement;
public class Main {
public static void main(String[] args) throws Exception {
Connection conn = getConnection();
conn.setAutoCommit(false);
Statement stmt = conn.createStatement();
stmt.executeUpdate("create table survey (id int, name CHAR(5) );");
stmt.executeUpdate("INSERT INTO survey(id, name)VALUES(111, "123456789")");
displayError(stmt.getWarnings());
// try to write more data for the name column.
displayError(stmt.getWarnings());
// since there were no errors, commit
conn.rumit();
ResultSet rs = stmt.executeQuery("SELECT * FROM survey");
outputResultSet(rs);
rs.close();
stmt.close();
conn.close();
}
public static void displayError(DataTruncation dataTruncation) {
if (dataTruncation != null) {
System.out.println("Data truncation error: ");
System.out.println(dataTruncation.getDataSize() + " bytes should have been ");
if (dataTruncation.getRead()) {
System.out.println("Read (Error:) ");
} else {
System.out.println("Written (Error:) ");
}
System.out.println(dataTruncation.getTransferSize()
+ " number of bytes of data actually transferred.");
}
}
public static void displayError(SQLWarning warning) {
while (warning != null) {
if (warning instanceof DataTruncation) {
displayError((DataTruncation) warning);
} else {
System.out.println(" Warning: " + warning.getMessage());
}
warning = warning.getNextWarning();
}
}
private static void outputResultSet(ResultSet rs) throws Exception {
ResultSetMetaData rsMetaData = rs.getMetaData();
int numberOfColumns = rsMetaData.getColumnCount();
for (int i = 1; i < numberOfColumns + 1; i++) {
String columnName = rsMetaData.getColumnName(i);
System.out.print(columnName + " ");
}
System.out.println();
System.out.println("----------------------");
while (rs.next()) {
for (int i = 1; i < numberOfColumns + 1; i++) {
System.out.print(rs.getString(i) + " ");
}
System.out.println();
}
}
private static Connection getConnection() throws Exception {
Class.forName("org.hsqldb.jdbcDriver");
String url = "jdbc:hsqldb:mem:data/tutorial";
return DriverManager.getConnection(url, "sa", "");
}
}