JDBC Tutorials - Herong's Tutorial Examples - v3.12, by Dr. Herong Yang
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
JDBC (Java Database Connectivity) Introduction
Installing and Running Java DB - Derby
Derby (Java DB) JDBC DataSource Objects
Java DB (Derby) - DML Statements
Java DB (Derby) - ResultSet Objects of Queries
Java DB (Derby) - PreparedStatement
MySQL JDBC Driver (MySQL Connector/J)
MySQL - Reference Implementation of JdbcRowSet
MySQL - JBDC CallableStatement
MySQL CLOB (Character Large Object) - TEXT
MySQL BLOB (Binary Large Object) - BLOB
Oracle Express Edition Installation on Windows
Oracle - Reference Implementation of JdbcRowSet
Oracle - JBDC CallableStatement
Oracle CLOB (Character Large Object) - TEXT
Oracle BLOB (Binary Large Object) - BLOB
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
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
Summary of JDBC Drivers and Database Servers