JDBC application programming

Writing a JDBC application has much in common with writing an SQL application in any other language.

In general, you need to do the following things:

Access the Java packages that contain JDBC methods.
Declare variables for sending data to or retrieving data from data server tables.
Connect to a data source.
Execute SQL statements.
Handle SQL errors and warnings.
Disconnect from the data source.

Although the tasks that you need to perform are similar to those in other languages, the way that you execute those tasks is somewhat different.

Example of a simple JDBC application
A simple JDBC application demonstrates the basic elements that JDBC applications need to include.
How JDBC applications connect to a data source
Before you can execute SQL statements in any SQL program, you must be connected to a data source.
Java packages for JDBC support
Before you can invoke JDBC methods, you need to be able to access all or parts of various Java packages that contain those methods.
Learning about a data source using DatabaseMetaData methods
The DatabaseMetaData interface contains methods that retrieve information about a data source. These methods are useful when you write generic applications that can access various data sources.
Variables in JDBC applications
As in any other Java application, when you write JDBC applications, you declare variables. In Java applications, those variables are known as Java identifiers.
Comments in a JDBC application
To document your JDBC program, you need to include comments. You can use Java comments outside of JDBC methods and Java or SQL comments in SQL statement strings.
JDBC interfaces for executing SQL
You execute SQL statements in a traditional SQL program to update data in tables, retrieve data from the tables, or call stored procedures. To perform the same functions in a JDBC program, you invoke methods.
Extended parameter information with the IBM Data Server Driver for JDBC and SQLJ
IBM Data Server Driver for JDBC and SQLJ-only methods and constants let you assign the default value or no value to table columns or ResultSet columns.
XML data in JDBC applications
In JDBC applications, you can store data in XML columns and retrieve data from XML columns.
Bidirectional (BiDi) text layout transformation
The IBM BiDi (bidirectional) engine can perform BiDi Layout transformation on data being stored and retrieved from the database.
Inserting data from file reference variables into tables in JDBC applications
You can use file reference variable objects with IBM Data Server Driver for JDBC and SQLJ type 2 connectivity on DB2 for z/OS® Version 9 or later to stream LOB or XML input data.
Transaction control in JDBC applications
In JDBC applications, as in other types of SQL applications, transaction control involves explicitly or implicitly committing and rolling back transactions, and setting the isolation level for transactions.
Exceptions and warnings under the IBM Data Server Driver for JDBC and SQLJ
In JDBC applications, SQL errors throw exceptions, which you handle using try/catch blocks. SQL warnings do not throw exceptions, so you need to invoke methods to check whether warnings occurred after you execute SQL statements.
Memory use for IBM Data Server Driver for IBM Data Server Driver for JDBC and SQLJ type 2 connectivity on DB2 for z/OS
In general, applications that use IBM Data Server Driver for JDBC and SQLJ type 2 connectivity require more memory than applications that use IBM Data Server Driver for JDBC and SQLJ type 4 connectivity.
Disconnecting from data sources in JDBC applications
When you have finished with a connection to a data source, it is essential that you close the connection to the data source. Doing this releases the Connection object's database and JDBC resources immediately.

Parent topic: Java application development for IBM data servers