JAVA Database Access

JDBC The Java Database Connectivity (JDBC) API is the industry standard for database- independent connectivity between the Java programming language and a wide range of databases – SQL databases and other tabular data sources, such as spreadsheets or flat files. The JDBC API provides a call-level API for SQL- based database access.

JDBC Using the JDBC, you can access virtually any data source, from relational databases to spreadsheets and flat files. JDBC technology also provides a common base on which tools and alternate interfaces can be built. The JDBC 3.0 API is comprised of two packages: – the java.sql package – the javax.sql package, which adds server-side capabilities – You automatically get both packages when you download the Java Platform Standard Edition (Java SE) 6.

JDBC Driver To use JDBC to access a database, you need to get the JDBC driver from the database vendor – For example, to use MySQL’s JDBC driver, i.e., Connector/J, you can download it from Connctor/J documetation: – tor-j.html

JDBC Driver Where you should install the driver? – When using it in a web application, put it in the dir WEB-INF/lib under your web application’s directory of TOMCAT – You can also put in the corresponding place inside the WAR file

MySQL JDBC Driver When you are using JDBC outside of an application server, the DriverManager class manages the establishment of Connections. The DriverManager needs to be told which JDBC drivers it should try to make Connections with. The easiest way to do this is to use Class.forName() on the class that implements the java.sql.Driver interface. With MySQL Connector/J, the name of this class is com.mysql.jdbc.Driver.

import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; public class LoadDriver { public static void main(String[] args) { try { Class.forName("com.mysql.jdbc.Driver").newInstance(); } catch (Exception ex) { // handle the error } Load the JDBC Driver for MySQL

Get the Connection object This example shows how you can obtain a Connection instance from the DriverManager. import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException;... try { Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/test?user=monty&password=“) // Do something with the Connection.... } catch (SQLException ex) { // handle any errors System.out.println("SQLException: " + ex.getMessage()); System.out.println("SQLState: " + ex.getSQLState()); System.out.println("VendorError: " + ex.getErrorCode()); } Database name Database user User password (no password in this case) Host name or ip address

// assume conn is an already created JDBC connection Statement stmt = null; ResultSet rs = null; try { stmt = conn.createStatement(); rs = stmt.executeQuery("SELECT foo FROM bar"); } // Now do something with the ResultSet.... } finally { if (rs != null) { try { rs.close(); } catch (SQLException sqlEx) { // ignore } rs = null; } if (stmt != null) { try { stmt.close(); } catch (SQLException sqlEx) { // ignore } stmt = null; } Execute query

More info MySQL JDBC driver tutorial – tor-j.html tor-j.html Sun’s JDBC tutorial – ics/index.html ics/index.html In depth tutorial from Sun and JGuru – abase/JDBCShortCourse/index.html