Inserting CLOB Values with setClob() Method

JDBC for MySQL - Herong's Tutorial Examples

∟MySQL CLOB (Character Large Object) - TEXT

∟Inserting CLOB Values with setClob() Method

This section describes how to insert CLOB values with the PreparedStatement.setClob() method.

If you want to insert a CLOB column with a character string that comes from a java.sql.Clob object, you can directly set the value with PreparedStatement.setClob() method.

To test this, I wrote the following program to copy some records with CLOB values as new records back into the same table. During the copy process, the CLOB values are also modified with some Clob object methods - The first 32 characters are converted to upper case characters.

/* MySqlClobSetClob.java
 * Copyright (c) HerongYang.com. All Rights Reserved.
 */
import java.io.*;
import java.sql.*;
public class MySqlClobSetClob {
  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();

// Deleting records for re-testing
      Statement sta = con.createStatement();
      sta.executeUpdate(
        "DELETE FROM Article WHERE Subject LIKE 'Copy of %'");

// Creating a PreparedStatement for inserting new records
      PreparedStatement ps = con.prepareStatement(
        "INSERT INTO Article (Subject, Body) VALUES (?,?)");

// Looping though the first 3 records
      ResultSet res = sta.executeQuery(
        "SELECT * FROM Article ORDER BY ID");
      int i = 0;
      while (res.next() && i<3) {
        i++;
        System.out.println("Copying record ID: "+res.getInt("ID"));
        String subject = res.getString("Subject");
        Clob body = res.getClob("Body");

// Modifying the Clob object
        String chuck = body.getSubString(1,32);
        chuck = chuck.toUpperCase();
        body.setString(1,chuck);

// Inserting a new record with setClob()
        ps.setString(1, "Copy of "+subject);
        ps.setClob(2,body);
        ps.executeUpdate();
      }
      ps.close();
      res.close();

// Checking the new records
      res = sta.executeQuery(
        "SELECT * FROM Article WHERE Subject LIKE 'Copy of %'");
      while (res.next()) {
        System.out.println("Record ID: "+res.getInt("ID"));
        System.out.println("   Subject = "+res.getString("Subject"));
        String body = res.getString("Body");
        if (body.length() > 100) body = body.substring(0,100);
        System.out.println("   Body = "+body+"...");
      }
      res.close();

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

The program performed exactly as I expected:

herong> java -cp .:mysql-connector-java.jar MySqlClobSetClob.java

Copying record ID: 1
Copying record ID: 2
Copying record ID: 5
Record ID: 6
   Subject = Copy of Test on INSERT statement
   Body = A BLOB (BINARY LARGE OBJECT) IS a large chunk of data which
is stored in a database....
Record ID: 7
   Subject = Copy of Test of the setString() method
   Body = HE IS WONDERFUL AND STRANGE AND who knows how old he is, he
thought. Never have I had such a strong ...
Record ID: 8
   Subject = Copy of Test of setCharacterStream() methods
   Body = /* MYSQLCLOBSETCHARACTERSTREAM.Java
 * Copyright (c) HerongYang.com. All Rights Reserved.
 */
...