Creating CallableStatement Objects with INOUT Parameters

JDBC for MySQL - Herong's Tutorial Examples

∟Creating CallableStatement Objects with INOUT Parameters

This section describes how to create CallableStatement objects with INOUT parameters.

MySQL procedures do support INOUT parameters, which should be handled like IN parameters and OUT parameters as shown in the previous tutorial.

In a previous tutorial, I defined a store procedure called, C2F(), with 2 INOUT parameters. The program below shows you to create a CallableStatement object to execute this stored procedure:

/* MySqlCallInoutParameter.java
 * Copyright (c) HerongYang.com. All Rights Reserved.
 */
import java.sql.*;
public class MySqlCallInoutParameter {
  public static void main(String [] args) {
    Connection con = null;
    try {
      com.mysql.cj.jdbc.MysqlDataSource ds
        = new com.mysql.cj.jdbc.MysqlDataSource();
      ds.setServerName("localhost");
      ds.setPortNumber(3306);
      ds.setDatabaseName("HerongDB");
      ds.setUser("Herong");
      ds.setPassword("TopSecret");
      ds.setServerTimezone(java.util.TimeZone.getDefault().getID());
      con = ds.getConnection();

// Create CallableStatement
      CallableStatement cs = con.prepareCall("CALL C2F(?,?)");

// Register INOUT parameters
      cs.registerOutParameter(1, java.sql.Types.REAL);
      cs.registerOutParameter(2, java.sql.Types.REAL);

// Provide values for INOUT parameters
      double celsius = 100.0;
      cs.setDouble(1,celsius);

// Execute the CALL statement and ignore result sets
      cs.executeUpdate();

// Retrieve values from INOUT parameters
      double fahrenheit = cs.getDouble(2);
      System.out.println("First test:");
      System.out.println("  Celsius = "+celsius);
      System.out.println("  Fahrenheit = "+fahrenheit);

// Second test
      celsius = 0.0;
      cs.setDouble(1,celsius);
      cs.executeUpdate();
      fahrenheit = cs.getDouble(2);
      System.out.println("First test:");
      System.out.println("  Celsius = "+celsius);
      System.out.println("  Fahrenheit = "+fahrenheit);

// Close resource
      cs.close();

      con.close();
    } catch (Exception e) {
      System.err.println("Exception: "+e.getMessage());
      e.printStackTrace();
    }
  }
}

The execution gave me one surprise. The second test failed with an error that I don' understand:

herong> java -cp .:mysql-connector-java.jar \
   MySqlCallInoutParameter.java

First test:
  Celsius = 100.0
  Fahrenheit = 212.0

Exception: Data truncated for column 'F' at row 1
java.sql.SQLException: Data truncated for column 'F' at row 1
   at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:998)
   at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3847)
   at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3783)
   at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2447)
   at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2594)
   at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2545)
   at com.mysql.jdbc.PreparedStatement.executeInternal(...)
   at com.mysql.jdbc.PreparedStatement.executeUpdate(...)
   ...
   at MySqlCallInoutParameter.main(MySqlCallInoutParameter.java:41)