120 lines
7.0 KiB
HTML
120 lines
7.0 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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<meta name="DC.Title" content="Example 2: Dynamically join database files without DDS" />
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<meta name="abstract" content="This example shows how to read only those records with secondary file records when dynamically joining database files without DDS." />
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<meta name="description" content="This example shows how to read only those records with secondary file records when dynamically joining database files without DDS." />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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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>Example 2: Dynamically join database files without DDS</title>
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</head>
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<body id="rbafodynjfex2"><a name="rbafodynjfex2"><!-- --></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">Example 2: Dynamically join database files without DDS</h1>
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<div><p>This example shows how to read only those records with secondary
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file records when dynamically joining database files without DDS.</p>
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<div class="section"><p>Assume that you want to join files FILEAB, FILECD, and FILEEF
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to select only those records with matching records in secondary files. Define
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a file JOINF and describe the format that should be used. Assume that the
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record formats for the files contain the following fields:</p>
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</div>
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<table cellpadding="4" cellspacing="0" border="1" class="tableborder"><tr><td>
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<table cellpadding="4" cellspacing="0" summary="" width="100%" border="0"><thead align="left"><tr><th align="left" valign="bottom" width="25%" id="d0e23">FILEAB</th>
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<th align="left" valign="bottom" width="25%" id="d0e25">FILECD</th>
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<th align="left" valign="bottom" width="25%" id="d0e27">FILEEF</th>
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<th align="left" valign="bottom" width="25%" id="d0e29">JOINF</th>
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</tr>
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</thead>
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<tbody><tr><td align="left" valign="top" width="25%" headers="d0e23 ">Abitm</td>
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<td align="left" valign="top" width="25%" headers="d0e25 ">Cditm</td>
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<td align="left" valign="top" width="25%" headers="d0e27 ">Efitm</td>
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<td align="left" valign="top" width="25%" headers="d0e29 ">Abitm</td>
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</tr>
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<tr><td align="left" valign="top" width="25%" headers="d0e23 ">Abord</td>
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<td align="left" valign="top" width="25%" headers="d0e25 ">Cddscp</td>
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<td align="left" valign="top" width="25%" headers="d0e27 ">Efcolr</td>
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<td align="left" valign="top" width="25%" headers="d0e29 ">Abord</td>
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</tr>
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<tr><td align="left" valign="top" width="25%" headers="d0e23 ">Abdat</td>
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<td align="left" valign="top" width="25%" headers="d0e25 ">Cdcolr</td>
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<td align="left" valign="top" width="25%" headers="d0e27 ">Efqty</td>
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<td align="left" valign="top" width="25%" headers="d0e29 ">Cddscp</td>
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</tr>
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<tr><td align="left" valign="top" width="25%" headers="d0e23 "> </td>
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<td align="left" valign="top" width="25%" headers="d0e25 "> </td>
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<td align="left" valign="top" width="25%" headers="d0e27 "> </td>
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<td align="left" valign="top" width="25%" headers="d0e29 ">Cdcolr</td>
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</tr>
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<tr><td align="left" valign="top" width="25%" headers="d0e23 "> </td>
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<td align="left" valign="top" width="25%" headers="d0e25 "> </td>
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<td align="left" valign="top" width="25%" headers="d0e27 "> </td>
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<td align="left" valign="top" width="25%" headers="d0e29 ">Efqty</td>
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</tr>
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</tbody>
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</table>
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</td></tr></table>
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<div class="section"><p>In this case, all field names in the files that make up the join
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file begin with a 2-character prefix (identical for all fields in the file)
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and end with a suffix that is identical across all the files (for example, <em>xxitm</em>).
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This makes all field names unique and avoids having to qualify them.</p>
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</div>
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<div class="section"><div class="p">The <em>xxitm</em> field allows the join from FILEAB to FILECD.
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The two fields <em>xxitm</em> and <em>xxcolr</em> allow the join from FILECD to
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FILEEF. A keyed sequence access path does not have to exist for these files.
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However, if a keyed sequence access path does exist, performance might improve
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significantly because the system will attempt to use the existing access path
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to arrange and select records, where it can. If access paths do not exist,
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the system automatically creates and maintains them as long as the file is
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open. <pre>OVRDBF FILE(JOINF) TOFILE(FILEAB) SHARE(*YES)
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OPNQRYF FILE(FILEAB FILECD FILEEF) +
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FORMAT(JOINF) +
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JFLD((ABITM CDITM)(CDITM EFITM) +
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(CDCOLR EFCOLR))
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CALL PGM(PGME) /* Created using file JOINF as input */
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CLOF OPNID(FILEAB)
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DLTOVR FILE(JOINF)</pre>
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</div>
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</div>
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<div class="section"><div class="p">The join field pairs do not have to be specified in the preceding
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order. For example, the same result is achieved with a JFLD parameter
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value of: <pre>JFLD((CDCOLR EFCOLR)(ABITM CDITM) (CDITM EFITM))</pre>
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</div>
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</div>
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<div class="section"><p>The attributes of each pair of join fields do not have to be identical.
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Normal padding of character fields and decimal alignment for numeric fields
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occurs automatically.</p>
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</div>
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<div class="section"><p>The JDFTVAL parameter is not specified so *NO is assumed and no
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default values are used to construct join records. If you specified JDFTVAL(*YES)
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and there is no record in file FILECD that has the same join field value as
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a record in file FILEAB, defaults are used for the <em>Cddscp</em> and <em>Cdcolr</em> fields
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to join to file FILEEF. Using these defaults, a matching record can be found
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in file FILEEF (depending on if the default value matches a record in the
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secondary file). If not, a default value appears for these files and for the <em>Efqty</em> field.</p>
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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="rbafodynjf.htm" title="The dynamic join function allows you to join files without having to first specify data description specifications (DDS) and create a join logical file.">Dynamically join database files without DDS</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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