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8.7 KiB
HTML
150 lines
8.7 KiB
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<meta name="DC.Title" content="Referential integrity and CL commands" />
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<meta name="abstract" content="Referential integrity affects the characteristics of some CL commands." />
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<title>Referential integrity and CL commands</title>
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<body id="rbaforzahfrc3"><a name="rbaforzahfrc3"><!-- --></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">Referential integrity and CL commands</h1>
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<div><p>Referential integrity affects the characteristics of some CL commands.</p>
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<ul><li class="liexpand"><strong>Add Physical File Member (ADDPFM)</strong>: <div class="p">In the case where a constraint
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relationship is defined between a dependent file and a parent file each having
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zero members: <ul><li>If a member is first added to the parent file, the constraint relationship
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remains in the defined state.</li>
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<li>If a member is then added to the dependent file, the foreign key access
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path is built, and a constraint relationship is established with the parent.</li>
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</ul>
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</div>
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</li>
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<li class="liexpand"><strong>Change Physical File (CHGPF)</strong>: <div class="p">When a constraint relationship
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exists for a file, you cannot change certain parameters available in the CHGPF
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command. The following parameters are restricted: <dl><dt class="dlterm">MAXMBRS</dt>
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<dd>The maximum number of members for a file that has a constraint relationship
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is one: MAXMBRS(1).</dd>
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<dt class="dlterm">CCSID</dt>
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<dd>The CCSID of a file that is not associated with a constraint, can be changed.
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If the file is associated with a constraint, the CCSID can only be changed
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to 65535.</dd>
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</dl>
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</div>
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</li>
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<li class="liexpand"><strong>Clear Physical File Member (CLRPFM)</strong>: <p>The CLRPFM command fails
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when issued for a parent file that contains records and is associated with
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an enabled referential constraint.</p>
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</li>
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<li class="liexpand"><strong>FORTRAN Force-End-Of-Data (FEOD)</strong>: <p>The FEOD operation fails when
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issued for a parent file that is associated with an enabled referential constraint
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relationship.</p>
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</li>
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<li class="liexpand"><strong>Create Duplicate Object (CRTDUPOBJ)</strong>: <div class="p"><img src="./delta.gif" alt="Start of change" />If CST(*NO)
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is specified, constraints will not be duplicated in the new file. If CST(*YES)
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is specified, constraints will be duplicated. The following rules describe
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how constraints are duplicated:<ul><li>If the parent file is duplicated either to the same library or to a different
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library, the system cross reference file is used to locate the dependent file
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of a defined referential constraint. Also, the system attempts to establish
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the constraint relationship.</li>
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<li>If the dependent file is duplicated, then the TOLIB is used to determine
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constraint relationships:<ul><li>If both the parent and dependent files are in the same library, the referential
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constraint relationship will be established with the parent file in the TOLIB.</li>
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<li>If the parent and dependent files are in different libraries, then the
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referential constraint relationship of the duplicated dependent file will
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be established with the original parent file</li>
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</ul>
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</li>
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</ul>
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<img src="./deltaend.gif" alt="End of change" /></div>
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</li>
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<li class="liexpand"><strong>Copy File (CPYF)</strong>: <p>When the CPYF command creates a new file and
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the original file has constraints, the constraints are not copied to the new
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file.</p>
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</li>
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<li class="liexpand"><strong>Move Object (MOVOBJ)</strong>: <p>The MOVOBJ command moves a file from one
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library to another. The system attempts to establish any defined referential
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constraints that can exist for the file in the new library.</p>
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</li>
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<li class="liexpand"><strong>Rename Object (RNMOBJ)</strong>: <p>The RNMOBJ command renames a file within
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the same library or renames a library.</p>
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<p>An attempt is made to establish
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any defined referential constraints that can exist for the renamed file or
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library.</p>
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</li>
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<li class="liexpand"><strong>Delete File (DLTF)</strong>: <div class="p">The DLTF command has an optional keyword
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that specifies how referential constraint relationships are handled. The RMVCST
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keyword applies to the dependent file in a constraint relationship. The keyword
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specifies how much of the constraint relationship of the dependent file is
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removed when the parent file is deleted: <dl><dt class="dlterm">*RESTRICT</dt>
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<dd>If a constraint relationship is defined or established between a parent
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file and dependent file, the parent file is not deleted and the constraint
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relationship is not removed. This is the default value.</dd>
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<dt class="dlterm">*REMOVE</dt>
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<dd>The parent file is deleted, and the constraint relationship and definition
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are removed. The constraint relationship between the parent file and the dependent
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file is removed. The dependent file's corresponding foreign key access path
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or paths, as well as the constraint definition, are removed.</dd>
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<dt class="dlterm">*KEEP</dt>
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<dd>The parent file is deleted, and the referential constraint relationship
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definition is left in the defined state. The dependent file's corresponding
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foreign key access path and constraint definition are not removed.</dd>
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</dl>
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</div>
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</li>
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<li class="liexpand"><strong>Remove Physical File Member (RMVM)</strong>: <p>When the member of a parent
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file in a constraint relationship is removed, the constraint relationship
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is put in the defined state. The foreign key access path and referential constraint
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definition are not removed. The parent key access path is removed because
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the parent member was removed; the parent constraint definition remains at
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the file level.</p>
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<p>When the member of a dependent file in a constraint
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relationship is removed, the constraint relationship is put in the defined
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state. The parent key access path and constraint definition are not removed.
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The foreign key access path is removed because the dependent member was removed;
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the referential constraint definition is not removed.</p>
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</li>
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<li class="liexpand"><strong>Save and restore commands</strong>: <p>If the parent file is restored to
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a library, the system uses the system cross reference files to locate the
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dependent file of a defined referential constraint. An attempt is made to
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establish the constraint relationship.</p>
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<div class="p">If the dependent file is restored,
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the TOLIB is used to determine constraint relationships: <ul><li>If both the parent and dependent files are in the same library, the referential
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constraint relationship is established with the parent file in the TOLIB.</li>
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<li>If the parent and dependent files are in different libraries, the referential
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constraint relationship of the duplicated dependent file is established with
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the original parent file.</li>
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</ul>
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</div>
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<p>The order of the restore of dependent and parent files within
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a constraint relationship does not matter (parent restored before dependent
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or dependent restored before parent). The constraint relationship will eventually
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be established.</p>
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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 class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rbaforzahfrca.htm" title="These topics discuss how to use referential constraints in your database to ensure that it contains only valid data.">Ensure data integrity with referential constraints</a></div>
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</div>
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</div>
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