Database node

This name identifies the appropriate database as it is known on the system on which this message flow is to run. The integration node connects to this database with user ID and password information that you have specified on the mqsisetdbparms command.

If the ESQL that is associated with this node includes a PASSTHRU statement or SELECT function and a database reference, you must specify a value for the Data Source property.

The ESQL file, which by default has the name <message_flow_name>.esql, contains ESQL for every node in the message flow that requires it. Each portion of code that is related to a specific node is known as a module. When you code ESQL statements that interact with tables, those tables are assumed to exist within this database. If they do not exist, a database error is generated by the integration node at run time.

Code ESQL statements to customize the behavior of the Database node in an ESQL file that is associated with the message flow in which you have included this instance of the Database node. If an ESQL file does not exist for this message flow, double-click the Database node, or right-click the node and click Open ESQL to create and open a new ESQL file in the ESQL editor view.

If an ESQL file exists, click Browse beside the Statement property to display the Module Selection dialog box, which lists the available Database node modules that are defined in the ESQL files that are accessible by this message flow (ESQL files can be defined in other, dependent, projects). Select the appropriate module and click OK. If no suitable modules are available, the list is empty.

If the module that you have specified does not exist, it is created for you and the editor displays it. If the file and the module exist, the editor highlights the correct module. If a module skeleton is created for this node in a new or existing ESQL file, it consists of the following ESQL. The default module name is shown in this example:

CREATE DATABASE MODULE <flow_name>_Database
       CREATE FUNCTION Main() RETURNS BOOLEAN
       BEGIN
               RETURN TRUE; 
       END;
END MODULE;

If you create your own ESQL module, create exactly this skeleton. You can update the default name, but ensure that the name that you specify matches the name of the corresponding node property Statement.

To customize this node, add your own ESQL after the BEGIN statement and before RETURN TRUE. You can use all the ESQL statements including SET, WHILE, DECLARE, and IF in this module, but (unlike the Compute node) the Database node propagates, unchanged, the message that it receives at its input terminal to its output terminal. Therefore, like the Filter node, you have only one message to refer to in a Database node.

• Automatic (the default). The message flow, of which the Database node is a part, is committed if it is successful; that is, the actions that you define in the ESQL module are performed and the message continues through the message flow. If the message flow fails, it is rolled back. If you select Automatic, the ability to commit or roll back the action of the Database node on the database depends on the success or failure of the entire message flow.
• Commit. To commit all uncommitted actions that are performed in this message flow on the database that is connected to this node, irrespective of the success or failure of the message flow as a whole, select Commit. The changes to the database are committed even if the message flow itself fails.

When you select the check box, the node handles all positive return codes from the database as errors, and generates exceptions in the same way that it does for the negative, or more serious, errors. If you do not select the check box, the node treats warnings as normal return codes, and does not raise an exception. The most significant warning raised is not found, which can be handled safely as a typical return code in most circumstances.

If you clear the check box, include ESQL to check for database errors that might be returned after each database call that you make (you can use SQLCODE and SQLSTATE to get this information). If an error has occurred, you must handle the error in the message flow to ensure the integrity of the integration node and the database; the error is ignored if you do not handle it through your own processing because you have chosen not to use the default error handling by the integration node. For example, you can include the ESQL THROW statement to throw an exception in this node, or you can use the Throw node to generate your own exception at a later point.