Tutorials : Building Web Applications Using Servlets and JSP :

From this step onwards the code is INDEPENDENT of the driver you are using

Statement stmt = con.createStatement();

At this point stmt object exists, but it does not have any SQL statement (query /update etc.) linked. To execute a Query we use the executeQuery method , similarly for an insert /update (and also any DDL statement) we use executeUpdate method.

String sql = "select USERID from USERTABLE where USERID ='guest' 
	and PASSWORD = 'guest' "; 
ResultSet rs = stmt.executeQuery(sql);

The query results are returned in a ResultSet object. A ResultSet object can be thought upon as a two dimensional array of objects. Every row in this array represents a single record selected from the table. The individual objects in one row correspond to the columns of the table.

The result set will contain all the rows selected from the table. We can go through individual rows using the "next()" method. Initially when the ResultSet is returned, the pointer or array index is before the first row. Every time you call next(), it will increment the pointer by 1 to point to the next row. If there is no next row to go to , next() will return false.

An example code to go through all the rows returned:

while (rs.next()) {
      // your processing logic
 }

The getXXX methods are used to retrieve a particular column value from the current row. To retrieve a String (database data types VARCHAR, CHAR and STRING depending on the DBMS and the driver) we use the getString() method. TheResultSet defines methods like getString for the major data types.

while (rs.next()) {
    String userId= rs.getString("USERID");
    String password = rs.getString("PASSWORD");
    }

One can also use the column number instead of name such as

String userId  = rs.getString(1);
String password  = rs.getString(2);

So far we covered the basic methods for accessing databases using JDBC. For advanced methods and method descriptions check out the JDBC API documentation.

How to Add Java Applets to Your Site

New on the Java Boutique:

New Review:

Time Management Made Easy with the Quartz Enterprise Job Scheduler
Why not just use the Java timer API? This open source scheduling API boasts simplicity, ease-of-integration, a well-rounded feature set, and it's free!

New Applet:

Reverse Complement
Reverse Complement is a simple applet that converts DNA or RNA sequences into three useful formats.

Elsewhere on internet.com:

WebDeveloper Java
Lots of Java information on webdeveloper.com

WDVL Java
Thorough Java resource at the Web Developer's Virtual Library.

ScriptSearch Java
Hundreds of free Java code files to download.

jGuru: Your View of the Java Universe
Customizable portal with online training, FAQs, regular news updates, and tutorials.