Common Errors with CallableStatement Parameters

<< MySQL - JBDC CallableStatement

<< JDBC Tutorials - Herong's Tutorial Notes

This section provides some error conditions on CallableStatement place holder parameters.

While testing CallableStatement objects with place holder parameters, I noticed two common errors as shown in this program:

/**
 * MySqlCallParameterError.java
 * Copyright (c) 2007 by Dr. Herong Yang. All rights reserved.
 */
import java.sql.*;
public class MySqlCallParameterError {
  public static void main(String [] args) {
    Connection con = null;
    try {
      com.mysql.jdbc.jdbc2.optional.MysqlDataSource ds 
        = new com.mysql.jdbc.jdbc2.optional.MysqlDataSource();
      ds.setServerName("localhost");
      ds.setPortNumber(3306);
      ds.setDatabaseName("HerongDB");
      ds.setUser("Herong");
      ds.setPassword("TopSecret");
      con = ds.getConnection();

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

// Provide values for IN parameters
// Error 2 - Forget to provide values for IN parameters
      String word = "Herong";
//    cs.setString(1,word);

// Register OUT parameters
// Error 1 - Can not register OUT parameters
      cs.registerOutParameter(1, java.sql.Types.VARCHAR);
      cs.registerOutParameter(2, java.sql.Types.VARCHAR);
      cs.registerOutParameter(3, java.sql.Types.INTEGER);

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

// Retrieve values from OUT parameters
      String reversed = cs.getString(2);
      int length = cs.getInt(3);
      System.out.println("Input word: "+word);
      System.out.println("Output word: "+reversed);
      System.out.println("Word length: "+length);

// Close resource
      cs.close();

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

Compile and run this program as is, you will get this error message at line 28, because registering an IN parameter as statement output parameter is not allowed:

C:\>javac -cp .;\local\lib\mysql-connector-java-5.0.7-bin.jar
  MySqlCallParameterError.java

C:\>java -cp .;\local\lib\mysql-connector-java-5.0.7-bin.jar
  MySqlCallParameterError

Exception: Parameter number 1 is not an OUT parameter
java.sql.SQLException: Parameter number 1 is not an OUT parameter
   at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:910)
   at com.mysql.jdbc.CallableStatement.checkIsOutputParam(...)
   at com.mysql.jdbc.CallableStatement.registerOutParameter(...)
   at MySqlCallParameterMissing.main(MySqlCallParameterError.java:30)

If you commented out this line, compile and run this program again, you will get a different error when calling cr.executeUpdate() at line 35. This time, no value was provided for the first parameter:

C:\>javac -cp .;\local\lib\mysql-connector-java-5.0.7-bin.jar
  MySqlCallParameterError.java

C:\>java -cp .;\local\lib\mysql-connector-java-5.0.7-bin.jar
  MySqlCallParameterError

Exception: No value specified for parameter 1
java.sql.SQLException: No value specified for parameter 1
   at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:910)
   at com.mysql.jdbc.PreparedStatement.fillSendPacket(...)
   at com.mysql.jdbc.PreparedStatement.executeUpdate(...)
   ...
   at MySqlCallParameterError.main(MySqlCallParameterError.java:35)

Sections in This Chapter

Overview of CallableStatement Objects

"CREATE PROCEDURE" - Creating a Simple Procedure

Creating Procedures with IN and OUT Parameters

Creating Procedures with INOUT Parameters

Creating Procedures with Multiple Queries

Creating CallableStatement Objects with prepareCall()

Capturing ResultSet with executeQuery()

Creating CallableStatement Objects with Parameters

Common Errors with CallableStatement Parameters

Creating CallableStatement Objects with INOUT Parameters

Retrieving Multiple ResultSet Objects

Executing Stored Procedures without Permission

getProcedures() - Listing Stored Procedures