282 lines
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HTML
282 lines
16 KiB
HTML
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<meta name="DC.Title" content="Example: Summarize data from database file records (grouping)" />
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<meta name="abstract" content="This example shows how to use the group processing functions to summarize data from existing database records." />
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<meta name="description" content="This example shows how to use the group processing functions to summarize data from existing database records." />
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<title>Example: Summarize data from database file records (grouping)</title>
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<body id="rbafogrpex1"><a name="rbafogrpex1"><!-- --></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: Summarize data from database file records (grouping)</h1>
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<div><p>This example shows how to use the group processing functions to
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summarize data from existing database records.</p>
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<div class="section"><p>Assume that you want to group the data by customer number and
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analyze the amount field. Your database file is FILEA and you create a file
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named FILEAA containing a record format with 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="d0e21">FILEA</th>
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<th align="left" valign="bottom" width="75%" id="d0e23">FILEAA</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="d0e21 ">Cust</td>
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<td align="left" valign="top" width="75%" headers="d0e23 ">Cust</td>
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</tr>
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<tr><td align="left" valign="top" width="25%" headers="d0e21 ">Type</td>
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<td align="left" valign="top" width="75%" headers="d0e23 ">Count (count of records per customer)</td>
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</tr>
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<tr><td align="left" valign="top" width="25%" headers="d0e21 ">Amt</td>
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<td align="left" valign="top" width="75%" headers="d0e23 ">Amtsum (summation of the amount field)</td>
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</tr>
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<tr><td align="left" valign="top" width="25%" headers="d0e21 "> </td>
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<td align="left" valign="top" width="75%" headers="d0e23 ">Amtavg (average of the amount field)</td>
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</tr>
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<tr><td align="left" valign="top" width="25%" headers="d0e21 "> </td>
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<td align="left" valign="top" width="75%" headers="d0e23 ">Amtmax (maximum value of the amount field)</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>When you define the fields in the new file, you must ensure that
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they are large enough to hold the results. For example, if the <em>Amt</em> field
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is defined as 5 digits, you might need to define the <em>Amtsum</em> field as
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7 digits. Any arithmetic overflow causes your program to end abnormally.</p>
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</div>
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<div class="section"><p>Assume that the records in FILEA have the following values:</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="center" valign="bottom" width="33.33333333333333%" id="d0e70">Cust</th>
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<th align="center" valign="bottom" width="33.33333333333333%" id="d0e72">Type</th>
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<th align="center" valign="bottom" width="33.33333333333333%" id="d0e74">Amt</th>
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</tr>
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</thead>
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<tbody><tr><td align="center" valign="top" width="33.33333333333333%" headers="d0e70 ">001</td>
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<td align="center" valign="top" width="33.33333333333333%" headers="d0e72 ">A</td>
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<td align="center" valign="top" width="33.33333333333333%" headers="d0e74 ">500.00</td>
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</tr>
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<tr><td align="center" valign="top" width="33.33333333333333%" headers="d0e70 ">001</td>
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<td align="center" valign="top" width="33.33333333333333%" headers="d0e72 ">B</td>
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<td align="center" valign="top" width="33.33333333333333%" headers="d0e74 ">700.00</td>
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</tr>
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<tr><td align="center" valign="top" width="33.33333333333333%" headers="d0e70 ">004</td>
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<td align="center" valign="top" width="33.33333333333333%" headers="d0e72 ">A</td>
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<td align="center" valign="top" width="33.33333333333333%" headers="d0e74 ">100.00</td>
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</tr>
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<tr><td align="center" valign="top" width="33.33333333333333%" headers="d0e70 ">002</td>
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<td align="center" valign="top" width="33.33333333333333%" headers="d0e72 ">A</td>
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<td align="center" valign="top" width="33.33333333333333%" headers="d0e74 ">1200.00</td>
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</tr>
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<tr><td align="center" valign="top" width="33.33333333333333%" headers="d0e70 ">003</td>
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<td align="center" valign="top" width="33.33333333333333%" headers="d0e72 ">B</td>
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<td align="center" valign="top" width="33.33333333333333%" headers="d0e74 ">900.00</td>
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</tr>
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<tr><td align="center" valign="top" width="33.33333333333333%" headers="d0e70 ">001</td>
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<td align="center" valign="top" width="33.33333333333333%" headers="d0e72 ">A</td>
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<td align="center" valign="top" width="33.33333333333333%" headers="d0e74 ">300.00</td>
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</tr>
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<tr><td align="center" valign="top" width="33.33333333333333%" headers="d0e70 ">004</td>
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<td align="center" valign="top" width="33.33333333333333%" headers="d0e72 ">A</td>
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<td align="center" valign="top" width="33.33333333333333%" headers="d0e74 ">300.00</td>
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</tr>
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<tr><td align="center" valign="top" width="33.33333333333333%" headers="d0e70 ">003</td>
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<td align="center" valign="top" width="33.33333333333333%" headers="d0e72 ">B</td>
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<td align="center" valign="top" width="33.33333333333333%" headers="d0e74 ">600.00</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"><div class="p">You then create a program (PGMG) using FILEAA as input to print
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the records.<pre>OVRDBF FILE(FILEAA) TOFILE(FILEA) SHARE(*YES)
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OPNQRYF FILE(FILEA) FORMAT(FILEAA) KEYFLD(CUST) +
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GRPFLD(CUST) MAPFLD((COUNT '%COUNT') +
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(AMTSUM '%SUM(AMT)') +
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(AMTAVG '%AVG(AMT)') +
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(AMTMAX '%MAX(AMT)'))
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CALL PGM(PGMG) /* Created using file FILEAA as input */
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CLOF OPNID(FILEA)
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DLTOVR FILE(FILEAA)</pre>
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</div>
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</div>
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<div class="section"><p>The records retrieved by the program appear as:</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="center" valign="bottom" width="20%" id="d0e150">Cust</th>
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<th align="center" valign="bottom" width="20%" id="d0e152">Count</th>
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<th align="center" valign="bottom" width="20%" id="d0e154">Amtsum</th>
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<th align="center" valign="bottom" width="20%" id="d0e156">Amtavg</th>
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<th align="center" valign="bottom" width="20%" id="d0e158">Amtmax</th>
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</tr>
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</thead>
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<tbody><tr><td align="center" valign="top" width="20%" headers="d0e150 ">001</td>
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<td align="center" valign="top" width="20%" headers="d0e152 ">3</td>
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<td align="center" valign="top" width="20%" headers="d0e154 ">1500.00</td>
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<td align="center" valign="top" width="20%" headers="d0e156 ">500.00</td>
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<td align="center" valign="top" width="20%" headers="d0e158 ">700.00</td>
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</tr>
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<tr><td align="center" valign="top" width="20%" headers="d0e150 ">002</td>
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<td align="center" valign="top" width="20%" headers="d0e152 ">1</td>
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<td align="center" valign="top" width="20%" headers="d0e154 ">1200.00</td>
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<td align="center" valign="top" width="20%" headers="d0e156 ">1200.00</td>
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<td align="center" valign="top" width="20%" headers="d0e158 ">1200.00</td>
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</tr>
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<tr><td align="center" valign="top" width="20%" headers="d0e150 ">003</td>
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<td align="center" valign="top" width="20%" headers="d0e152 ">2</td>
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<td align="center" valign="top" width="20%" headers="d0e154 ">1500.00</td>
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<td align="center" valign="top" width="20%" headers="d0e156 ">750.00</td>
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<td align="center" valign="top" width="20%" headers="d0e158 ">900.00</td>
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</tr>
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<tr><td align="center" valign="top" width="20%" headers="d0e150 ">004</td>
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<td align="center" valign="top" width="20%" headers="d0e152 ">2</td>
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<td align="center" valign="top" width="20%" headers="d0e154 ">400.00</td>
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<td align="center" valign="top" width="20%" headers="d0e156 ">200.00</td>
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<td align="center" valign="top" width="20%" headers="d0e158 ">300.00</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"> <div class="note"><span class="notetitle">Note:</span> If you specify the GRPFLD parameter, the groups might not
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appear in ascending sequence. To ensure a specific sequence, you should specify
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the KEYFLD parameter.</div>
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</div>
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<div class="section"><div class="p">Assume that you want to print only the summary records in this
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example in which the <em>Amtsum</em> value is greater than 700.00. Because the <em>Amtsum</em> field
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is an aggregate field for a given customer, use the GRPSLT parameter to specify
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selection after grouping. Add the GRPSLT parameter: <pre>GRPSLT('AMTSUM *GT 700.00')</pre>
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</div>
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</div>
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<div class="section"><p>The records retrieved by your program are:</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="center" valign="bottom" width="20%" id="d0e232">Cust</th>
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<th align="center" valign="bottom" width="20%" id="d0e234">Count</th>
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<th align="center" valign="bottom" width="20%" id="d0e236">Amtsum</th>
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<th align="center" valign="bottom" width="20%" id="d0e238">Amtavg</th>
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<th align="center" valign="bottom" width="20%" id="d0e240">Amtmax</th>
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</tr>
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</thead>
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<tbody><tr><td align="center" valign="top" width="20%" headers="d0e232 ">001</td>
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<td align="center" valign="top" width="20%" headers="d0e234 ">3</td>
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<td align="center" valign="top" width="20%" headers="d0e236 ">1500.00</td>
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<td align="center" valign="top" width="20%" headers="d0e238 ">500.00</td>
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<td align="center" valign="top" width="20%" headers="d0e240 ">700.00</td>
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</tr>
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<tr><td align="center" valign="top" width="20%" headers="d0e232 ">002</td>
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<td align="center" valign="top" width="20%" headers="d0e234 ">1</td>
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<td align="center" valign="top" width="20%" headers="d0e236 ">1200.00</td>
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<td align="center" valign="top" width="20%" headers="d0e238 ">1200.00</td>
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<td align="center" valign="top" width="20%" headers="d0e240 ">1200.00</td>
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</tr>
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<tr><td align="center" valign="top" width="20%" headers="d0e232 ">003</td>
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<td align="center" valign="top" width="20%" headers="d0e234 ">2</td>
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<td align="center" valign="top" width="20%" headers="d0e236 ">1500.00</td>
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<td align="center" valign="top" width="20%" headers="d0e238 ">750.00</td>
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<td align="center" valign="top" width="20%" headers="d0e240 ">900.00</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>The Open Query File (OPNQRYF) command supports selection both
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before grouping (QRYSLT parameter) and after grouping (GRPSLT parameter).</p>
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</div>
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<div class="section"><div class="p">Assume that you want to select additional customer records in
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which the <em>Type</em> field is equal to A. Because <em>Type</em> is a field
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in the record format for file FILEA and not an aggregate field, you add the
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QRYSLT statement to select before grouping as follows: <pre>QRYSLT('TYPE *EQ "A" ')</pre>
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</div>
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</div>
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<div class="section"><div class="note"><span class="notetitle">Note:</span> Fields used for selection do not have to appear in the format
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processed by the program.</div>
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</div>
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<div class="section"><p>The records retrieved by your program are:</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="center" valign="bottom" width="20%" id="d0e305">Cust</th>
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<th align="center" valign="bottom" width="20%" id="d0e307">Count</th>
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<th align="center" valign="bottom" width="20%" id="d0e309">Amtsum</th>
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<th align="center" valign="bottom" width="20%" id="d0e311">Amtavg</th>
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<th align="center" valign="bottom" width="20%" id="d0e313">Amtmax</th>
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</tr>
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</thead>
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<tbody><tr><td align="center" valign="top" width="20%" headers="d0e305 ">001</td>
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<td align="center" valign="top" width="20%" headers="d0e307 ">2</td>
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<td align="center" valign="top" width="20%" headers="d0e309 ">800.00</td>
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<td align="center" valign="top" width="20%" headers="d0e311 ">400.00</td>
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<td align="center" valign="top" width="20%" headers="d0e313 ">500.00</td>
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</tr>
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<tr><td align="center" valign="top" width="20%" headers="d0e305 ">002</td>
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<td align="center" valign="top" width="20%" headers="d0e307 ">1</td>
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<td align="center" valign="top" width="20%" headers="d0e309 ">1200.00</td>
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<td align="center" valign="top" width="20%" headers="d0e311 ">1200.00</td>
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<td align="center" valign="top" width="20%" headers="d0e313 ">1200.00</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"><div class="note"><span class="notetitle">Note:</span> The values for CUST 001 changed because the selection took
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place before the grouping took place.</div>
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</div>
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<div class="section"><div class="p">Assume that you want to arrange the output
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by the <em>Amtavg</em> field in descending sequence, in addition to the previous
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QRYSLT parameter value. You can do this by changing the KEYFLD parameter on
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the OPNQRYF command as: <pre>KEYFLD((AMTAVG *DESCEND))</pre>
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</div>
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</div>
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<div class="section"><p>The records retrieved by your program are:</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="center" valign="bottom" width="20%" id="d0e369">Cust</th>
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<th align="center" valign="bottom" width="20%" id="d0e371">Count</th>
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<th align="center" valign="bottom" width="20%" id="d0e373">Amtsum</th>
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<th align="center" valign="bottom" width="20%" id="d0e375">Amtavg</th>
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<th align="center" valign="bottom" width="20%" id="d0e377">Amtmax</th>
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</tr>
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</thead>
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<tbody><tr><td align="center" valign="top" width="20%" headers="d0e369 ">002</td>
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<td align="center" valign="top" width="20%" headers="d0e371 ">1</td>
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<td align="center" valign="top" width="20%" headers="d0e373 ">1200.00</td>
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<td align="center" valign="top" width="20%" headers="d0e375 ">1200.00</td>
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<td align="center" valign="top" width="20%" headers="d0e377 ">1200.00</td>
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</tr>
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<tr><td align="center" valign="top" width="20%" headers="d0e369 ">001</td>
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<td align="center" valign="top" width="20%" headers="d0e371 ">2</td>
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<td align="center" valign="top" width="20%" headers="d0e373 ">800.00</td>
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<td align="center" valign="top" width="20%" headers="d0e375 ">400.00</td>
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<td align="center" valign="top" width="20%" headers="d0e377 ">500.00</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>
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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="rbafogrp.htm" title="The group processing function allows you to summarize data from existing database records.">Summarize data from database file records (grouping)</a></div>
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</div>
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</div>
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</body>
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</html> |