89 lines
5.2 KiB
HTML
89 lines
5.2 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 name="DC.Type" content="reference" />
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<meta name="DC.Title" content="UNIQUE (Unique) keyword for physical and logical files" />
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<meta name="abstract" content="Use this file-level keyword to specify that records with duplicate key values are not allowed within a member of this physical or logical file." />
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<meta name="description" content="Use this file-level keyword to specify that records with duplicate key values are not allowed within a member of this physical or logical file." />
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<meta name="DC.subject" content="UNIQUE (Unique) keyword" />
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<meta name="keywords" content="UNIQUE (Unique) keyword" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2001, 2006" />
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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>Physical and Logical Files, UNIQUE</title>
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</head>
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<body id="tduniqu"><a name="tduniqu"><!-- --></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">UNIQUE (Unique) keyword for physical and logical files</h1>
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<div><p>Use this file-level keyword to specify that records with duplicate
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key values are not allowed within a member of this physical or logical file.</p>
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<div class="section"><p>You can specify whether null key values are
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to be considered as duplicates using the parameter. Any insertions or additions
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of new records, or updates to existing records, which might result in a duplicate
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key, are rejected. The application program issuing the write or the update
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operation receives an error message. When a workstation user is using data
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file utility (DFU), a message is displayed at the workstation. A copy file
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command that copies records with duplicate keys in this file is not completed.</p>
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<div class="p">The
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format of this keyword is: <pre>UNIQUE[(*INCNULL | *EXCNULL)]</pre>
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The
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parameter is optional. When specified, it determines whether null key values
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cause duplicates. *INCNULL is the default and indicates to include null values
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when determining duplicates. *EXCNULL, when specified, indicates to exclude
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null values when determining duplicates.</div>
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<p>When a logical file based on
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a physical file has the UNIQUE keyword, the physical file member or members
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cannot have duplicate key values.</p>
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<p>When you specify the UNIQUE keyword
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for a physical or logical file, you must specify the MAINT(*IMMED) parameter
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value on the Create Physical File (CRTPF) or Create Logical File (CRTLF) command
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that creates the file. This means that the access path is maintained immediately
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when changes are made.</p>
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<p>If you do not specify the UNIQUE
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keyword, records with duplicate key values are sequenced in the order you
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specify. If you specify the FIFO keyword, they are sequenced in first-in first-out
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order. If you specify the LIFO keyword, they are sequenced in last-in first-out
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order. If you specify the FCFO keyword, they are sequenced in first-changed
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first-out order. If you do not specify FIFO, LIFO or FCFO, the order in which
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the records are sequenced is not guaranteed.</p>
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<p>You cannot specify the
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UNIQUE keyword with the FIFO, LIFO, FCFO, or REFACCPTH keywords.</p>
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</div>
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<div class="example"><h4 class="sectiontitle">Example</h4><p>The following example shows how to specify
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the UNIQUE keyword for a logical file.</p>
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<pre>|...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
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00010A*
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00020A* SAMPLE LOGICAL FILE (CUSMSTL)
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00030A*
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00040A UNIQUE
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00050A R CUSREC PFILE(CUSMSTP)
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00060A TEXT('Logical File Master Record')
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00070A CUST
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00080A NAME
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00090A ADDR
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00100A K CUST
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A</pre>
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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="rzakbmstlfkeyw.htm" title="This topic lists valid keyword entries for describing physical and logical files. They are typed in positions 45 through 80 (functions).">Keyword entries for physical and logical files (positions 45 through 80)</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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