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Chapter 18 JDBC and Database Connection Pooling

Core Note

JDBC is not an acronym.

Although a complete tutorial on database programming is beyond the

scope of this chapter, I'll cover the basics of using JDBC here, assuming

you are already familiar with SQL. For more details on JDBC, see

http://java.sun.com/products/jdbc/

, the on line API for 

java.sql

,

or the JDBC tutorial at 

http://java.sun.com/docs/books/tutorial/

jdbc/

. If you don't already have access to a database, you might find

mySQL a good choice for practice. It is free for non Microsoft operating

systems as well as for educational or research use on Windows. For details,

see 

http://www.mysql.com/

.

18.1 Basic Steps in Using JDBC

There are seven standard steps in querying databases:

1. Load the JDBC driver.

2. Define the connection URL.

3. Establish the connection.

4. Create a statement object.

5. Execute a query or update.

6. Process the results.

7. Close the connection.

Here are some details of the process.

Load the Driver

The driver is the piece of software that knows how to talk to the actual data 

base server. To load the driver, all you need to do is to load the appropriate

class; a 

static

 block in the class itself automatically makes a driver instance

and registers it with the JDBC driver manager. To make your code as flexible

as possible, it is best to avoid hard coding the reference to the class name. 

These requirements bring up two interesting questions. First, how do you

load a class without making an instance of it? Second, how can you refer to a

class whose name isn't known when the code is compiled? The answer to

both questions is: use 

Class.forName

. This method takes a string represent 

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