67 lines
4.4 KiB
HTML
67 lines
4.4 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="DC.Type" content="concept" />
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<meta name="DC.Title" content="Record format description" />
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<meta name="abstract" content="When you describe a database file to the system, you describe the two major parts of the file: the record format and the access path. The record format describes the order of the fields in each record." />
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<meta name="description" content="When you describe a database file to the system, you describe the two major parts of the file: the record format and the access path. The record format describes the order of the fields in each record." />
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<meta name="DC.subject" content="describing, record format, example" />
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<meta name="keywords" content="describing, record format, example" />
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<meta name="DC.Relation" scheme="URI" content="rbafodeffi.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="rbaforecft" />
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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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<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>Record format description</title>
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</head>
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<body id="rbaforecft"><a name="rbaforecft"><!-- --></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">Record format description</h1>
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<div><p>When you describe a database file to the system, you describe the
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two major parts of the file: the record format and the access path. The record
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format describes the order of the fields in each record. </p>
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<p>The record format also describes each field in detail, including: length,
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data type (for example, packed decimal or character), validity checks, text
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description, and other information.</p>
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<p>The following example shows the relationship between the record format
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and the records in a physical file:</p>
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<br /><img src="rbafo501.gif" alt="Specifications for record format" /><br /><p>In this example of specifications for record format ITMMST, there are three
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fields. Field <em>ITEM</em> is zoned decimal, five digits, with no decimal position.
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Field <em>DESCRP</em> is character, with 18 positions. Field <em>PRICE</em> is
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zoned decimal, five digits, with two decimal positions.</p>
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<p>A physical file can have only one record format. The record format in a
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physical file describes the way the data is actually stored.</p>
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<p>A logical file contains no data. Logical files are used to arrange data
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from one or more physical files into different formats and sequences. For
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example, a logical file can change the order of the fields in the physical
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file, or present to the program only some of the fields stored in the physical
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file.</p>
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<p>A logical file record format can change the length and data type of fields
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stored in physical files. The system does the necessary conversion between
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the physical file field description and the logical file field description.
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For example, a physical file can describe a field <em>FLDA</em> as a packed
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decimal field of five digits and a logical file using <em>FLDA</em> might redefine
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it as a zoned decimal field of seven digits. In this case, when
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your program uses the logical file to read a record, the system automatically
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converts (unpack) <em>FLDA</em> to zoned decimal 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="rbafodeffi.htm" title="This topic discusses the ways to describe records in database files.">How database files are described</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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