113 lines
7.1 KiB
HTML
113 lines
7.1 KiB
HTML
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<!DOCTYPE html
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<meta name="DC.Title" content="Concatenated fields" />
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<meta name="abstract" content="Using the CONCAT keyword, you can combine two or more fields from a physical file record format to make one field in a logical file record format." />
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<meta name="description" content="Using the CONCAT keyword, you can combine two or more fields from a physical file record format to make one field in a logical file record format." />
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<title>Concatenated fields</title>
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</head>
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<body id="rbafoconfd"><a name="rbafoconfd"><!-- --></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">Concatenated fields</h1>
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<div><p>Using the CONCAT keyword, you can combine two or more fields from
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a physical file record format to make one field in a logical file record format. </p>
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<p> For example, a physical file record format contains the fields <em>Month</em>, <em>Day</em>,
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and <em>Year</em>. For a logical file, you concatenate these fields into one
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field, <em>Date</em>.</p>
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<div class="p">The field length for the resulting concatenated field is the sum of the
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lengths of the included fields (unless the fields in the physical file are
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binary or packed decimal, in which case they are changed to zoned decimal).
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The field length of the resulting field is automatically calculated by the
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system. A concatenated field can have: <ul><li>Column headings</li>
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<li>Validity checking</li>
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<li>Text description</li>
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<li>Edit code or edit word (numeric concatenated fields only)</li>
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</ul>
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<div class="note"><span class="notetitle">Note:</span> This editing and validity checking information is not used by the
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database management system but is retrieved when field descriptions from the
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database file are referred to in a display or printer file.</div>
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</div>
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<div class="p">When fields are concatenated, the data types can change (the resulting
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data type is automatically determined by the system). The following rules
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and restrictions apply: <ul><li>The operating system assigns the data type based on
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the data types of the fields that are being concatenated.</li>
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<li>The maximum length of a concatenated field varies depending on the data
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type of the concatenated field and the length of the fields being concatenated.
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If the concatenated field is zoned decimal (S), its total length cannot exceed
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31 bytes; if it is character (A), its total length cannot exceed 32 766 bytes.</li>
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<li>In join logical files, the fields to be concatenated must be from the
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same physical file. The first field specified on the CONCAT keyword identifies
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which physical file is to be used. The first field must, therefore, be unique
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among the physical files on which the logical file is based, or you must also
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specify the JREF keyword to specify which physical file to use.</li>
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<li>The use of a concatenated field must be I (input only) if the concatenated
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field is variable length. Otherwise, the use can be B (both input and output).</li>
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<li>REFSHIFT cannot be specified on a concatenated field that has been assigned
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a data type of O or J.</li>
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<li>If any of the fields contain the null value, the result of concatenation
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is the null value.</li>
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</ul>
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<div class="note"><span class="notetitle">Note:</span> For information about concatenating DBCS fields, see <a href="rbafoappdbcs.htm#rbafoappdbcs">Double-byte character set considerations</a>.</div>
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When
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only numeric fields are concatenated, the sign of the last field in the group
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is used as the sign of the concatenated field. <div class="note"><span class="notetitle">Notes:</span> <ol><li>Numeric fields with decimal precision other than zero cannot be included
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in a concatenated field.</li>
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<li>Date, time, timestamp, and floating-point fields cannot be included in
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a concatenated field.</li>
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</ol>
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</div>
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</div>
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<p>The following example shows the field description in data description specifications
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(DDS) for concatenation. (The CONCAT keyword is used to specify the fields
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to concatenate.)</p>
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<pre>|...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
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A
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00101A MONTH
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00102A DAY
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00103A YEAR
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00104A DATE CONCAT(MONTH DAY YEAR)
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A</pre>
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<div class="p">In this example, the logical file record format includes the separate fields
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of <em>Month</em>, <em>Day</em>, and <em>Year</em>, as well as the concatenated <em>Date</em> field.
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Any of the following formats can be used: <ul><li>A format with the separate fields of <em>Month</em>, <em>Day</em>, and <em>Year</em></li>
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<li>A format with only the concatenated <em>Date</em> field</li>
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<li>A format with the separate fields <em>Month</em>, <em>Day</em>, <em>Year</em> and
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the concatenated <em>Date</em> field</li>
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</ul>
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</div>
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<p>When both separate and concatenated fields exist in the format, any updates
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to the fields are processed in the sequence in which the DDS is specified.
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In the previous example, if the <em>Date</em> field contained 103188 and the <em>Month</em> field
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is changed to 12, when the record is updated, the month in the <em>Date</em> field
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would be used. The updated record would contain 103188. If the <em>Date</em> field
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were specified first, the updated record would contain 123188.</p>
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<p>Concatenated fields can also be used as key fields and select/omit fields.</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="rbafodescdrv.htm" title="Fields in a logical file can be derived from fields in the physical file on which the logical file is based or from fields in the same logical file.">Derive new fields from existing fields</a></div>
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</div>
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</div>
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