如何调用存储过程和准备好的声明

Question

在下面的代码中，我想调用一个存储过程并执行一个Query。我在statement.executeUpdate();面临错误请帮助解决它。我不知道哪里出错了。

public void Dbexe() {

    Connection connection;
    connection = DatabaseConnection.getCon();
     CallableStatement stmt;
    try {
        stmt = connection.prepareCall("{CALL optg.Ld_SOpp}");
        stmt.executeUpdate();
        stmt.close();
    } catch (SQLException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }

     System.out.println("Stored Procedure executed");

     //PreparedStatement statement = null;
    // ResultSet rs = null;

    try{


     PreparedStatement statement;
    try {
        statement = connection.prepareStatement("MERGE INTO OPTG.R_VAL AS TARGET USING" + 
              ........... +
             "");

         statement.executeUpdate(); //Here the exception is thrown  
         statement.close();

         connection.commit();
         connection.close();


    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }   

    // statement = connection.prepareStatement(query);

     //statement.close();

    }

    finally{

        System.out.println("Data is copied to the  Table");

            }    

 }