62 lines
4.8 KiB
HTML
62 lines
4.8 KiB
HTML
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<meta name="DC.Title" content="Use floating-point fields in database file access paths" />
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<meta name="abstract" content="The collating sequence for records in a keyed database file depends on the presence of the SIGNED, UNSIGNED, and ABSVAL keywords in data description specifications (DDS). For floating-point fields, the sign is the farthest-left bit, the exponent is next, and the significant is last." />
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<title>Use floating-point fields in database file access paths</title>
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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">Use floating-point fields in database file access paths</h1>
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<div><p>The collating sequence for records in a keyed database file depends
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on the presence of the SIGNED, UNSIGNED, and ABSVAL keywords in data description
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specifications (DDS). For floating-point fields, the sign is the farthest-left
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bit, the exponent is next, and the significant is last.</p>
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<div class="p">The collating sequence with UNSIGNED specified is: <ul><li>Positive real numbers—positive infinity</li>
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<li>Negative real numbers—negative infinity</li>
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</ul>
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</div>
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<p>A floating-point key field with the SIGNED keyword specified, or defaulted
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to, in DDS has an algebraic numeric sequence. The collating sequence is negative
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infinity—real numbers—positive infinity.</p>
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<p>A floating-point key field with the ABSVAL keyword specified in DDS has
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an absolute value numeric sequence.</p>
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<div class="p">The following floating-point collating sequences are observed: <ul><li>Zero (positive or negative) collates in the same manner as any other positive/negative
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real number.</li>
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<li>Negative zero collates before positive zero for SIGNED sequences.</li>
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<li>Negative and positive zero collate the same for ABSVAL sequences.</li>
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</ul>
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</div>
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<p>You cannot use not-a-number (*NAN) values in key fields. If you attempt
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this, and a *NAN value is detected in a key field during file creation, the
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file is not created.</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="rbafoapath.htm" title="These topics discuss the different ways of describing access paths for database files.">Describe access paths for database files</a></div>
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</div>
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