IBM DB2 User Manual

Data retrieval in JDBC applications
In JDBC applications, you retrieve data using ResultSet objects. A ResultSet
represents the result set of a query.
Retrieving data from tables using the Statement.executeQuery
method
To retrieve data from a table using a SELECT statement with no parameter
markers, you can use the Statement.executeQuery method.
This method returns a result table in a ResultSet object. After you obtain the result
table, you need to use ResultSet methods to move through the result table and
obtain the individual column values from each row.
With the IBM Data Server Driver for JDBC and SQLJ, you can also use the
Statement.executeQuery method to retrieve a result set from a stored procedure
call, if that stored procedure returns only one result set. If the stored procedure
returns multiple result sets, you need to use the Statement.execute method.
This topic discusses the simplest kind of ResultSet, which is a read-only ResultSet
in which you can only move forward, one row at a time. The IBM Data Server
Driver for JDBC and SQLJ also supports updatable and scrollable ResultSets.
To retrieve rows from a table using a SELECT statement with no parameter
markers, you need to perform these steps:
1. Invoke the Connection.createStatement method to create a Statement object.
2. Invoke the Statement.executeQuery method to obtain the result table from the
SELECT statement in a ResultSet object.
3. In a loop, position the cursor using the next method, and retrieve data from
each column of the current row of the ResultSet object using getXXX methods.
XXX represents a data type.
4. Invoke the ResultSet.close method to close the ResultSet object.
5. Invoke the Statement.close method to close the Statement object when you
have finished using that object.
The following code demonstrates how to retrieve all rows from the employee table.
The numbers to the right of selected statements correspond to the
previously-described steps.
Related concepts
String empNo;
Connection con;
Statement stmt;
ResultSet rs;
...
stmt = con.createStatement(); // Create a Statement object 1
rs = stmt.executeQuery("SELECT EMPNO FROM EMPLOYEE"); 2
// Get the result table from the query
while (rs.next()) { // Position the cursor 3
empNo = rs.getString(1); // Retrieve only the first column value
System.out.println("Employee number="+empNo);
// Print the column value
}
rs.close(); // Close the ResultSet 4
stmt.close(); // Close the Statement 5
Figure 12. Using Statement.executeQuery
32 Application Programming Guide and Reference for Java
™

IBM DB2 Specifications

General

Developer	IBM
Initial Release	1983
License	Proprietary
Written in	C, C++
Category	Database Management System (RDBMS)
Operating System	Linux, Windows
Programming Languages	C, C++
Data Models	Relational
Editions	Community, Standard, Advanced
Key Features	high availability, scalability

Summary

JDBC application programming

How JDBC applications connect to a data source

Explains how JDBC applications establish a connection to a data source.

Connecting to a data source using the DriverManager interface with the IBM Data Server Driver for JDBC and SQLJ

Details on connecting to a data source using the DriverManager interface.

Connecting to a data source using the DataSource interface

Details on connecting to a data source using the DataSource interface for portability.

How to determine which type of IBM Data Server Driver for JDBC and SQLJ connectivity to use

Guidance on selecting the appropriate IBM Data Server Driver connectivity type.

JDBC interfaces for executing SQL

Explains the JDBC interfaces used for executing SQL statements.

Creating and modifying database objects using the Statement.executeUpdate method

Updating data in tables using the PreparedStatement.executeUpdate method

Data retrieval in JDBC applications

Explains how to retrieve data from tables using ResultSet objects.

Retrieving data from tables using the Statement.executeQuery method

Retrieving data from tables using the PreparedStatement.executeQuery method

SQLJ application programming

Connecting to a data source using SQLJ

Explains how to connect to a data source in an SQLJ program.

SQLJ connection technique 1: JDBC DriverManager interface

Details SQLJ connection using the JDBC DriverManager interface.

SQLJ connection technique 2: JDBC DriverManager interface

Details SQLJ connection using the JDBC DriverManager interface.

SQLJ connection technique 3: JDBC DataSource interface

Details SQLJ connection using the JDBC DataSource interface.

SQLJ connection technique 4: JDBC DataSource interface

Details SQLJ connection using the JDBC DataSource interface.

SQL statement execution in SQLJ applications

Describes executing SQL statements within SQLJ.

Creating and modifying DB2 objects in an SQLJ application

Performing positioned UPDATE and DELETE operations in an SQLJ application

Details performing positioned UPDATE and DELETE operations in SQLJ.

Data retrieval in SQLJ applications

Explains how to retrieve result sets using SQLJ iterators.

Using a named iterator in an SQLJ application

Using a positioned iterator in an SQLJ application

Using scrollable iterators in an SQLJ application

Controlling the execution of SQL statements in SQLJ

Describes how to control SQL statement execution in SQLJ.

Handling SQL errors and warnings in SQLJ applications

Details handling SQL errors and warnings in SQLJ.

Handling SQL errors in an SQLJ application

Explains how to handle SQL errors in SQLJ applications.

Java stored procedures and user-defined functions

Setting up the environment for Java routines

Details on setting up the WLM and Java environments for Java routines.

Setting up the WLM application environment for Java routines

Describes setting up WLM application environments for Java routines.

WLM address space startup procedure for Java routines

Provides an example of a WLM address space startup procedure for Java routines.

Run-time environment for Java routines

Explains the run-time environment setup for Java routines.

Definition of a Java routine to DB2

Explains how to define a Java routine to DB2.

Writing a Java stored procedure to return result sets

Explains how to write Java stored procedures that return multiple result sets.

Preparing and running JDBC and SQLJ programs

Program preparation for JDBC programs

Details the preparation process for JDBC programs.

Program preparation for SQLJ programs

Outlines the preparation process for SQLJ programs.

Binding SQLJ applications to access multiple database servers

Explains how to bind SQLJ applications to multiple DB2 servers.

Preparing Java routines with no SQLJ clauses to run from a JAR file

Steps to prepare Java routines from JAR files.

Preparing Java routines with SQLJ clauses to run from a JAR file

Recommended method for preparing SQLJ routines from JAR files.

Running JDBC and SQLJ programs

Explains how to run JDBC and SQLJ programs.

JDBC and SQLJ reference information

Data types that map to database data types in Java applications

Summarizes mappings of Java data types to database data types.

Data types for updating table columns

Data types for retrieval from table columns

Data types for calling stored procedures and user-defined functions

Data types in Java stored procedures and user-defined functions

Properties for the IBM Data Server Driver for JDBC and SQLJ

Defines how connection properties define the connection to a data source.

Common IBM Data Server Driver for JDBC and SQLJ properties for all supported database products

Lists properties common to all supported database products.

Common IBM Data Server Driver for JDBC and SQLJ properties for DB2 servers

Lists properties specific to DB2 servers.

currentQueryOptimization

Specifies a value that controls the class of query optimization.

Common IBM Data Server Driver for JDBC and SQLJ properties for DB2 for z/OS and IDS

Lists properties specific to DB2 for z/OS and IDS database servers.

Common IBM Data Server Driver for JDBC and SQLJ properties for DB2 Database for Linux, UNIX, and Windows

Lists properties specific to DB2 Database for Linux, UNIX, and Windows servers.

Installing the IBM Data Server Driver for JDBC and SQLJ

Installing the IBM Data Server Driver for JDBC and SQLJ as part of a DB2 installation

Details on installing the driver as part of DB2 installation.

Jobs for loading the IBM Data Server Driver for JDBC and SQLJ libraries

Describes jobs for loading the driver libraries.

Environment variables for the IBM Data Server Driver for JDBC and SQLJ

Lists required environment variables for the driver.

Customization of IBM Data Server Driver for JDBC and SQLJ configuration properties

Explains how to customize driver configuration properties.

Enabling the DB2-supplied stored procedures and defining the tables used by the IBM Data Server Driver for JDBC and SQLJ

Creating the WLM address space startup procedure for the IBM Data Server Driver for JDBC and SQLJ stored procedures

DB2Binder utility

Explains the DB2Binder utility for binding DB2 packages.

DB2Binder option descriptions

Migrating from the JDBC/SQLJ Driver for OS/390 and z/OS to the IBM Data Server Driver for JDBC and SQLJ

Prerequisites for migrating to the IBM Data Server Driver for JDBC and SQLJ

To migrate to the IBM Data Server Driver for JDBC and SQLJ, follow these steps

Provides steps for migrating to the IBM Data Server Driver.

Conversion of JDBC/SQLJ Driver for OS/390 and z/OS properties to IBM Data Server Driver for JDBC and SQLJ properties

DB2T4XAIndoubtUtil for distributed transactions with DB2 UDB for OS/390 and z/OS Version 7 servers

Verify the installation of the IBM Data Server Driver for JDBC and SQLJ

Explains how to verify the driver installation.

Security under the IBM Data Server Driver for JDBC and SQLJ

You can determine the security mechanism that is in effect for a connection by calling the DB2Connection.getDB2SecurityMechanism method

User ID and password security under the IBM Data Server Driver for JDBC and SQLJ

Details user ID and password security for JDBC connections.

User ID-only security under the IBM Data Server Driver for JDBC and SQLJ

Explains user ID-only security for JDBC connections.

Encrypted password, user ID, or user ID and password security under the IBM Data Server Driver for JDBC and SQLJ

Covers encrypted security for passwords and user IDs.

Kerberos security under the IBM Data Server Driver for JDBC and SQLJ

Details Kerberos security support for JDBC and SQLJ.

IBM Data Server Driver for JDBC and SQLJ trusted context support

IBM Data Server Driver for JDBC and SQLJ support for SSL

Configuring connections under the IBM Data Server Driver for JDBC and SQLJ to use SSL

Details how to configure connections for SSL usage.

Configuring the Java Runtime Environment to use SSL

Explains how to configure the Java Runtime Environment for SSL.

Security for preparing SQLJ applications with the IBM Data Server Driver for JDBC and SQLJ

JDBC connection concentrator and workload balancing

Java applications that use IBM Data Server Driver for JDBC and SQLJ type 4 connectivity to access DB2 for z/OS or IBM Informix Dynamic Server can take advantage of the connection concentrator and workload balancing functions.

Example of enabling the IBM Data Server Driver for JDBC and SQLJ connection concentrator for DB2 for z/OS servers

Provides an example of enabling connection concentrator for DB2 for z/OS.

Techniques for monitoring IBM Data Server Driver for JDBC and SQLJ connection concentrator and workload balancing

Problem diagnosis with the IBM Data Server Driver for JDBC and SQLJ

Collecting JDBC trace data

Explains procedures for starting JDBC trace collection.

Collecting SQLJ trace data during customization or bind

Example of using configuration properties to start a JDBC trace

Example of a trace program under the IBM Data Server Driver for JDBC and SQLJ

System monitoring for the IBM Data Server Driver for JDBC and SQLJ

To assist you in monitoring the performance of your applications with the IBM Data Server Driver for JDBC and SQLJ, the driver provides two methods to collect information for a connection.

To collect system monitoring data using the DB2SystemMonitor interface: Perform these basic steps:

Outlines basic steps for collecting system monitoring data.

Example of using DB2SystemMonitor methods to collect system monitoring data

Glossary