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128 lines
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<meta name="DC.Title" content="Commands, statements, and operations that you cannot use in trigger programs" />
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<meta name="abstract" content="A trigger program cannot include some commands, statements, and operations." />
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<title>Commands, statements, and operations that you cannot use in trigger
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programs</title>
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</head>
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<body id="rbafotrgncmd"><a name="rbafotrgncmd"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Commands, statements, and operations that you cannot use in trigger
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programs</h1>
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<div><p>A trigger program cannot include some commands, statements, and
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operations. </p>
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<div class="section"><p>The system returns an exception if you use these: </p>
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</div>
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<div class="section"><div class="p"> <ul><li>The commitment definition associated with the insert, update, delete,
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or read operation that called the trigger does not allow the COMMIT operation.
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The COMMIT operation <em>is</em> allowed for any other commitment definition
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in the job.</li>
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<li>The commitment definition associated with the insert, update, delete,
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or read operation that called the trigger does not allow the ROLLBACK operation.
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The ROLLBACK operation <em>is</em> allowed for any other commitment definition
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in the job.</li>
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<li>The SQL CONNECT, DISCONNECT, SET CONNECTION, and RELEASE statements <em>are
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not</em> allowed.</li>
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<li>The commitment definition associated with the insert, update, delete,
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or read operation that called the trigger does not allow the ENDCMTCTL CL
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command. The ENDCMTCTL CL command <em>is</em> allowed for any other commitment
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definition in the job.</li>
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<li>An attempt to add a local API commitment resource (QTNADDCR) to the same
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commitment definition associated with the insert, update, delete, or read
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operation that called the trigger.</li>
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<li>An attempt to do any input/output operation to a file that a trigger program
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has opened with *SHARE and is the file that caused the trigger program to
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be called.</li>
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<li>The called trigger program that uses the same commitment definition as
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the insert, update, delete, or read operation that called the trigger and
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that already has an existing remote resource. However, the system puts the
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entire transaction into a rollback-required state: <ul><li>If the trigger program fails and signals an escape message AND</li>
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<li>Any remote resource was updated during the non-primary commit cycle for
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either a non-<span class="keyword">iSeries™</span> location
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or for one that is at a pre-Version 3 Release 2 level.</li>
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<li>The trigger program can add a remote resource to the commitment definition
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associated with the insert, update, delete, or read operation that called
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the trigger. This allows for LU62 remote resources (protected </li>
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<li>conversation) and DFM remote resources (DDM file open), but not DRDA<sup>®</sup> remote resources.</li>
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<li>If a failure occurs when changing a remote resource from a trigger program,
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the trigger program must end by signalling an escape message. This allows
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the system to ensure that the entire transaction, for all remote locations,
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properly rolls back. If the trigger program does not end with an escape message,
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the databases on the various remote locations might become inconsistent.</li>
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<li>A commit lock level of the application program is passed to the trigger
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program. Run the trigger program under the same lock level as the application
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program.</li>
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<li>The trigger program and application program can run in the same or different
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activation groups. Compile the trigger program with ACTGRP(*CALLER) to achieve
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consistency between the trigger program and the application program.</li>
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<li>A trigger program calls other programs or it can be nested (that is, a
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statement in a trigger program causes the calling of another trigger program).
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In addition, a trigger program itself can call a trigger program. The maximum
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trigger nested level for insert, update, delete, or read is 200. When the
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trigger program runs under commitment control, the following situations will
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result in an error: <ul><li>Any update of the same record that has already been changed by the change
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operation or by an operation in the trigger program.</li>
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<li>Conflicting operations on the same record within one change operation.
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For example, the change operation inserts a record, then the record is deleted
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by the trigger program.</li>
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</ul>
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<div class="p"><div class="note"><span class="notetitle">Notes:</span> <ol><li>If the change operation is not running under commitment control, the system
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always protects the change operation. However, the system does not monitor
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updating the same record within the trigger program.</li>
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<li>The ALWREPCHG(*NO|YES) parameter of the Add Physical File Trigger (ADDPFTRG)
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command controls repeated changes under commitment control. Changing from
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the default value to ALWREPCHG(*YES) allows the same record or updated record
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associated with the trigger program to repeatedly change.</li>
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</ol>
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</div>
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</div>
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</li>
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<li>The Allow Repeated Change ALWREPCHG(*YES) parameter on the Add Physical
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File Trigger (ADDPFTRG) command also affects trigger programs defined to be
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called before insert and update database operations. If the trigger program
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updates the new record in the trigger buffer and ALWREPCHG(*YES) is specified,
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the actual insert or update operation on the associated physical file uses
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the modified new record image. This option can be helpful in trigger programs
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that are designed for data validation and data correction. Because the trigger
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program receives physical file record images (even for logical files), it
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can change any field of that record image.</li>
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<li>The trigger program is called for each row that is changed in or read
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from the physical file.</li>
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<li>If the physical file or the dependent logical file is opened for insert
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SEQONLY(*YES) processing, and the physical file has an insert trigger program
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associated with it, the system changes the open to SEQONLY(*NO) so it can
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call the trigger program for each row that is inserted.</li>
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</ul>
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</li>
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</ul>
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</div>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rbaforzahftre.htm" title="Trigger programs can be very powerful. But you must take caution when coding trigger programs.">Precautions to take when coding trigger programs</a></div>
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</div>
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</div>
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</body>
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</html>
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