94 lines
5.4 KiB
HTML
94 lines
5.4 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="security" content="public" />
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<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="Use *NONE in the key field when creating a DDS file" />
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<meta name="abstract" content="Key fields having the same key position should not be compared under two conditions." />
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<meta name="description" content="Key fields having the same key position should not be compared under two conditions." />
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<meta name="DC.subject" content="logical files, *NONE key field" />
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<meta name="keywords" content="logical files, *NONE key field" />
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<meta name="DC.Relation" scheme="URI" content="lkeynm.htm" />
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<meta name="DC.Relation" scheme="URI" content="logfileviewex.htm" />
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<meta name="DC.Relation" scheme="URI" content="logfileviewex2.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2001, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2001, 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="nonekeyfield" />
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<meta name="DC.Language" content="en-us" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Use *NONE in the key field when creating a DDS file</title>
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</head>
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<body id="nonekeyfield"><a name="nonekeyfield"><!-- --></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">Use *NONE in the key field when creating a DDS file</h1>
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<div><p>Key fields having the same key position should not be compared
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under two conditions.</p>
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<div class="p">The two conditions are: <ul><li>The key fields do not have the same field attributes (data type, length,
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decimal positions, or access path keywords at the field level).</li>
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<li>The key fields have the same attributes, but you do not want them to be
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merged and sequenced together.</li>
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</ul>
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</div>
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<p>To avoid unwanted comparisons between key fields, specify *NONE in place
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of one of them and move the displaced key field to the next key position.
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The operating system compares the values of key positions before and after
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*NONE, but retrieves the affected records in the order in which the record
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formats are specified in the DDS for the logical file.</p>
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<p>You can specify *NONE two or more times on the following lines to displace
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a key field to a key position for which a comparison of key field attributes
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is relevant to your application.</p>
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<p><a href="#nonekeyfield__cfig6a">Figure 1</a> shows *NONE as the key field.</p>
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<div class="fignone" id="nonekeyfield__cfig6a"><a name="nonekeyfield__cfig6a"><!-- --></a><span class="figcap">Figure 1. Specify *NONE as the key field</span><pre>|...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
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A R RECORD1 PFILE(PF1)
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A FIELD1 6A
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A FIELD2 4A
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A FIELD3 10A
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A K FIELD1
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A K FIELD2
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A K FIELD3
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A
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A R RECORD2 PFILE(PF2)
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A FLD1 3A
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A FLD2 4A
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A FLD3 12A
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A K *NONE
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A K FLD2
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A
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A R RECORD3 PFILE(PF3)
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A F1 6A
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A F2 4A
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A F3 10A
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A K F1
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A K F2
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A K F3
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A</pre>
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</div>
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<p>In <a href="#nonekeyfield__cfig6a">Figure 1</a>, the attributes for FIELD2,
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FLD2, and F2, must be identical. Because you specified *NONE
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for the first key field of the second record, then FIELD1 and F1 (first key
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field of the first record and first key field of the third record) must have
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identical attributes. FIELD3 and F3 must also have identical attributes; there
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is no corresponding field in the second record format.</p>
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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="lkeynm.htm" title="When you specify K in position 17, the name specified in positions 19 through 28 is a key field name.">Key field name</a></div>
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</div>
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<div class="relref"><strong>Related reference</strong><br />
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<div><a href="logfileviewex.htm" title="In this example, a logical file views records of two physical files through two different record formats: CLSHST (class history) and JOBHST (job history).">Specify the key field (example 1)</a></div>
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<div><a href="logfileviewex2.htm" title="In this example, a logical file views the same two physical files as in Example 1, but the second record format in the logical file has *NONE specified in key position 2.">Specify the key field (example 2)</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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