JDBC Tutorials - Herong's Tutorial Examples - v3.12, by Dr. Herong Yang
ResultSet Cursor Initial Position: Before First Row
This section describes the ResultSet cursor initial position: before first row. next() should be called to move the cursor to the first row.
Right after the ResultSet object is returned from the executeQuery() call, the ResultSet cursor is positioned before the first row. You need to call next() once to move the cursor to the first row. If you missed this call, you will get an error message as shown by this sample program:
/* DerbyResultSetNoNext.java * Copyright (c) HerongYang.com. All Rights Reserved. */ import java.sql.*; public class DerbyResultSetNoNext { public static void main(String [] args) { Connection con = null; try { con = DriverManager.getConnection("jdbc:derby://localhost/TestDB"); Statement sta = con.createStatement(); // Catch the ResultSet object ResultSet res = sta.executeQuery("SELECT * FROM Profile"); // Skip calling next() // res.next(); // Try to get column values String firstName = res.getString("FirstName"); String lastName = res.getString("LastName"); // Close ResultSet res.close(); sta.close(); con.close(); } catch (Exception e) { System.err.println("Exception: "+e.getMessage()); } } }
Run this program to see the error if res.next() is not called after executeQuery():
Exception: Invalid operation at current cursor position.
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
ResultSet Cursor and Scrollability
►ResultSet Cursor Initial Position: Before First Row
Retrieving Column Values with getXXX() Methods
ResultSet Default Type: Forward-only
Scrollable ResultSet and Moving Cursor Backward
ResultSet Objects with Update Capability
insertRow() - Inserting New Rows through ResultSet Objects
updateXXX() - Updating Column Values for Row Update or Insert
deleteRow() - Deleting Rows through ResultSet Objects
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
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