Using DB2

IBM DB2 Express-C for Linux HOWTO
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# 20. Using DB2

This section gives you the basic information you need to start working with DB2 Express-C on Linux. It includes instructions on issuing DB2 commands and SQL statements from the command line, as well as the commands you need to start the DB2 Control Center and the DB2 Information Center. For more information about general DB2 usage, please investigate the DB2 manuals and Information Center.

## 20.1. DB2 Control Center

To start the DB2 Control Center:

1. Ensure you are logged on to your Linux workstation using either the DB2 Administration Server user ID (dasusr1 by default) or the DB2 instance user ID (db2inst1 by default). If you use the su command to change to one of those users, ensure you include the -l parameter to initialize the proper user environment.

2. Start the X server, if it is not already started.

3. Start a terminal session, or type Alt + F2 to bring up the Linux "Run Command" dialog.

4. Type db2cc to start the DB2 Control Center.

The left side of the DB2 Control Center provides an object based view of the database objects that you have catalogued, including DB2 instances and databases on other DB2 servers.

One way to add, edit, or drop database objects is to right-click on the object to bring up a context menu.

## 20.2. DB2 Information Center

As mentioned above, the new DB2 Information Center is a revamped documentation display system that now encapsulates the task, concept and reference information required to properly run DB2 . It can be installed locally, on an intranet server, or accessed directly from the ibm.com hosting service.

To start the DB2 Information Center:

1. Ensure you are logged on to your Linux workstation using either the DB2 Administration Server user ID (dasusr1 by default) or the DB2 instance user ID (db2inst1 by default). If you use the su command to change to one of those users, ensure you include the -l parameter to initialize the proper user environment.

2. Ensure that the X server is started, as the Information Center requires a Web browser.

3. Issue one of the launch commands:

   - db2icdocs
   - db2help
   - db2ic
   - db2cc -ic

Alternatively, you can launch the Information Center from within the Control Center (or any of the other GUI tools), by clicking an item under the "Help" menu, or by clicking on the "?" (question mark) icon.

If you did not install the DB2 Information Center, or have not configured your tools to use a different server, then these commands will launch a detected browser, and take you directly to the IBM hosted DB2 Information Center at http://publib.boulder.ibm.com/infocenter/db2help/.

## 20.3. DB2 command line processor (CLP)

If you are logged on to your Linux workstation using either the DB2 Administration Server user ID or the DB2 instance user ID, you can issue DB2 commands and SQL statements from the command line.

If this is your first time using DB2 , I would suggest creating the DB2 sample database. The sample database is used throughout the DB2 documentation and is required by most of the sample applications.

To create the sample database, you can either select the Create the SAMPLE database option from the DB2 First Steps launchpad, or by issuing the db2sampl command from the command line.

Before you can issue an SQL statement, you have to connect to a database. To connect to a database, enter the command:

    db2 CONNECT TO database USER userID USING password

To connect to a database, and have DB2 prompt you for the password, issue the command:

    db2 CONNECT TO database USER userID

To connect to a database using the default user ID, issue the command:

    db2 CONNECT TO database

Once you have connected to a database, you can then issue SQL statements or DB2 commands against that database. For example, to select all of the rows from the EMPLOYEE table in the SAMPLE database, issue this command:

    db2 "SELECT * FROM employee"

You can avoid typing db2 as the prefix for every SQL statement and DB2 command by issuing DB2 commands using the Command Line Processor (CLP). To start the CLP, issue the db2 command by itself from a Linux command line terminal. DB2 provides the following prompt:

    You can issue database manager commands and SQL statements
    from the command prompt. For example:
      db2 => connect to sample
      db2 => bind sample.bnd

    For general help, type: ?.
    For command help, type: ? command, where command can be
    the first few keywords of a database manager command. For example:
    ? CATALOG DATABASE for help on the CATALOG DATABASE command
    ? CATALOG          for help on all of the CATALOG commands.

    To exit db2 interactive mode, type QUIT at the command prompt. Outside
    interactive mode, all commands must be prefixed with 'db2'.
    To list the current command option settings, type LIST COMMAND OPTIONS.

    For more detailed help, refer to the Online Reference Manual.

    db2 =>

Some users prefer to avoid the CLP because it prevents using the command line history features of the shell.

Some users claim that running the CLP within an Emacs shell gives them the best of both worlds: they get command line history, and they don't have to escape commands that contain lots of quotation marks and brackets, but your mileage may vary.

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