69 lines
4.9 KiB
HTML
69 lines
4.9 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="concept" />
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<meta name="DC.Title" content="Considerations for writing a high-level language program" />
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<meta name="abstract" content="There are certain considerations for writing a high-level language program." />
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<meta name="description" content="There are certain considerations for writing a high-level language program." />
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<meta name="DC.subject" content="writing, high-level language program, high-level language (HLL) program, writing considerations, HLL (high-level language) program" />
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<meta name="keywords" content="writing, high-level language program, high-level language (HLL) program, writing considerations, HLL (high-level language) program" />
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<meta name="DC.Relation" scheme="URI" content="rbafoopnqf.htm" />
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<meta name="DC.Relation" scheme="URI" content="rbafoufinf.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<title>Considerations for writing a high-level language program</title>
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</head>
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<body id="rbafochllp"><a name="rbafochllp"><!-- --></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">Considerations for writing a high-level language program</h1>
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<div><p>There are certain considerations for writing a high-level
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language program.</p>
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<p>If you omit the FORMAT parameter, your high-level language program is coded
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as if you were directly accessing the database file. Selection or sequencing
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occurs external to your program, and the program receives the selected records
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in the order you specified. The program does not receive records that are
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omitted by your selection values. This same function occurs if you process
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through a logical file with select/omit values.</p>
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<p>If you use the FORMAT parameter, your program specifies the same file name
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used on the FORMAT parameter. The program is written as if this file contained
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actual data.</p>
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<p>If you read the file sequentially, your high-level language can automatically
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specify that the key fields are ignored. Normally you write the program as
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if it were reading records in arrival sequence. If the KEYFLD parameter is
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used on the Open Query File (OPNQRYF) command, you receive a diagnostic message,
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which can be ignored.</p>
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<p>If you process the file randomly by keys, your high-level language probably
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requires a key specification. If you have selection values, it can prevent
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your program from accessing a record that exists in the database. A <samp class="codeph">Record
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not found</samp> condition can occur on a random read whether the OPNQRYF
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command was used or whether a logical file created using DDS select/omit logic
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was used.</p>
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<p>In some cases, you can monitor exceptions caused by mapping errors such
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as arithmetic overflow, but it is better to define the attributes of all fields
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to correctly handle the results.</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="rbafoopnqf.htm" title="The Open Query File (OPNQRYF) command is a control language (CL) command that allows you to perform many data processing functions on database files. These topics discuss how to create a query using the OPNQRYF command, how to specify parameters for its major functions, and how to use it with your high-level language program.">Use Open Query File (OPNQRYF) command</a></div>
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</div>
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<div class="reltasks"><strong>Related tasks</strong><br />
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<div><a href="rbafoufinf.htm" title="The Open Query File (OPNQRYF) command does the record selection and your program processes only the records that meet the selection values. You can use this approach to select a set of records, return records in a different sequence than they are stored, or both.">Use an existing record format in the file</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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