Retrieving CLOB Values with getClob() Method

This section describes how to retrieve CLOB values with the ResultSet.getClob() method.

If you like to work with java.sql.Clob objects, you can retrieve CLOB values with the getClob() method on ResultSet objects. The Clob object offers some interesting methods:

Here is my test program on getClob() method:

/* SqlServerClobGetClob.java
 * Copyright (c) HerongYang.com. All Rights Reserved.
 */
import java.io.*;
import java.sql.*;
public class SqlServerClobGetClob {
  public static void main(String [] args) {
    Connection con = null;
    try {
      com.microsoft.sqlserver.jdbc.SQLServerDataSource ds
        = new com.microsoft.sqlserver.jdbc.SQLServerDataSource();
      ds.setServerName("localhost");
//      ds.setPortNumber(60782);
      ds.setInstanceName("SQLEXPRESS");
      ds.setDatabaseName("AdventureWorks2019");
      ds.setUser("Herong");
      ds.setPassword("T0pSecret");
      con = ds.getConnection();

// Retrieving CLOB value with getClob()
      Statement sta = con.createStatement();
      ResultSet res = sta.executeQuery("SELECT * FROM Article");
      int i = 0;
      while (res.next() && i<3) {
        i++;
        System.out.println("Record ID: "+res.getInt("ID"));
        System.out.println("   Subject = "+res.getString("Subject"));
        Clob bodyOut = res.getClob("Body");
        int length = (int) bodyOut.length();
        System.out.println("   Body Size = "+length);
        String body = bodyOut.getSubString(1, length);
        if (body.length() > 100) body = body.substring(0,100);
        System.out.println("   Body = "+body+"...");
        bodyOut.free(); // new in JDBC 4.0
      }
      res.close();

      sta.close();
      con.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

The output confirms that the getClob() method and Clob objects are not hard to use:

herong> java -cp .;mssql-jdbc-9.4.1.jre16.jar SqlServerClobGetClob

Record ID: 1
   Subject = Test on INSERT statement
   Body Size = 84
   Body = A BLOB (Binary Large OBject) is a large chunk of data which
is stored in a database....
Record ID: 2
   Subject = Test of the setString() method
   Body Size = 304
   Body = He is wonderful and strange and who knows how old he is, he
thought. Never have I had such a strong ...
Record ID: 5
   Subject = Test of setCharacterStream() methods
   Body Size = 2235
   Body = /* SqlServerClobSetCharacterStream.java
 * Copyright (c) HerongYang.com. All Rights Reserved.
...

Table of Contents

 About This Book

 JDBC (Java Database Connectivity) Introduction

 JDK (Java SE) Installation

 Microsoft SQL Server Express Edition

 Microsoft JDBC Driver for SQL Server

 Microsoft JDBC Driver - Query Statements and Result Sets

 Microsoft JDBC Driver - DatabaseMetaData Object

 Microsoft JDBC Driver - DDL Statements

 Microsoft JDBC Driver - DML Statements

 SQL Server - PreparedStatement

SQL Server CLOB (Character Large Object) - TEXT

 Overview of CLOB (Character Large Object)

 Create Tables with CLOB Columns

 Inserting CLOB Values with SQL INSERT Statements

 Inserting CLOB Values with setString() Method

 Inserting CLOB Values with setCharacterStream() Method

 Closing InputStream Too Early on setCharacterStream()

 Retrieving CLOB Values with getString() Method

 Retrieving CLOB Values with getCharacterStream() Method

Retrieving CLOB Values with getClob() Method

 Inserting CLOB Values with setClob() Method

 SQL Server BLOB (Binary Large Object) - BLOB

 Using Connection Pool with JDBC

 JDBC-ODBC Bridge Driver - sun.jdbc.odbc.JdbcOdbcDriver

 JDBC-ODBC Bridge Driver - Flat Text Files

 JDBC-ODBC Bridge Driver - MS Access

 JDBC-ODBC Bridge Driver - MS SQL Server

 Archived Tutorials

 References

 Full Version in PDF/EPUB