117 lines
6.6 KiB
HTML
117 lines
6.6 KiB
HTML
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<title>Use host structures in COBOL applications that use SQL</title>
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</head>
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<body id="rzajphoststructurecobol"><a name="rzajphoststructurecobol"><!-- --></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">Use host structures in COBOL applications that use SQL</h1>
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<div><p>A <em>host structure</em> is a named set of host variables that is
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defined in your program's DATA DIVISION.</p>
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<div class="section"><p>Host structures have a maximum of two levels, even though the
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host structure might itself occur within a multilevel structure. An exception
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is the declaration of a varying-length character string, which requires another
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level that must be level 49.</p>
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</div>
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<div class="section"><p>A host structure name can be a group name whose subordinate levels
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name basic data items. For example: </p>
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<pre>01 A
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02 B
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03 C1 PICTURE ...
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03 C2 PICTURE ...</pre>
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</div>
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<div class="section"><p>In this example, B is the name of a host structure consisting
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of the basic items C1 and C2.</p>
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</div>
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<div class="section"><p>When writing an SQL statement using a qualified host variable
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name (for example, to identify a field within a structure), use the name of
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the structure followed by a period and the name of the field. For example,
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specify B.C1 rather than C1 OF B or C1 IN B. However, this guideline applies
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only to qualified names within SQL statements; you cannot use this technique
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for writing qualified names in COBOL statements.</p>
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</div>
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<div class="section"><p>A host structure is considered complete if any of the following
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items are found: </p>
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<ul><li>A COBOL item that must begin in area A</li>
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<li>Any SQL statement (except SQL INCLUDE)</li>
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</ul>
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</div>
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<div class="section"><p>After the host structure is defined, you can refer to it in an
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SQL statement instead of listing the several host variables (that is, the
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names of the data items that comprise the host structure).</p>
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</div>
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<div class="section"><p>For example, you can retrieve all column values from selected
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rows of the table CORPDATA.EMPLOYEE with: </p>
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<pre>01 PEMPL.
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10 EMPNO PIC X(6).
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10 FIRSTNME.
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49 FIRSTNME-LEN PIC S9(4) USAGE BINARY.
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49 FIRSTNME-TEXT PIC X(12).
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10 MIDINIT PIC X(1).
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10 LASTNAME.
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49 LASTNAME-LEN PIC S9(4) USAGE BINARY.
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49 LASTNAME-TEXT PIC X(15).
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10 WORKDEPT PIC X(3).
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…
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MOVE "000220" TO EMPNO.
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…
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EXEC SQL
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<strong>SELECT</strong> *
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<strong>INTO</strong> :PEMPL
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<strong>FROM</strong> CORPDATA.EMPLOYEE
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<strong>WHERE</strong> EMPNO = :EMPNO
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END-EXEC.</pre>
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</div>
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<div class="section"><p>Notice that in the declaration of PEMPL, two varying-length string
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elements are included in the structure: FIRSTNME and LASTNAME.</p>
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</div>
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</div>
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<div>
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<ul class="ullinks">
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<li class="ulchildlink"><strong><a href="rzajphoststruccobol.htm">Host structure in COBOL applications that use SQL</a></strong><br />
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The following figure shows the syntax for the valid host structure.</li>
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<li class="ulchildlink"><strong><a href="rzajphostindicatorcobol.htm">Host structure indicator array in COBOL applications that use SQL</a></strong><br />
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The following figure shows the syntax for valid indicator array declarations.</li>
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<li class="ulchildlink"><strong><a href="rzajphoststrucarraycobol.htm">Use host structure arrays in COBOL applications that use SQL</a></strong><br />
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A host structure array is a named set of host variables that is defined in the program's Data Division and has an OCCURS clause.</li>
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<li class="ulchildlink"><strong><a href="rzajphoststrucappcobol.htm">Host structure array in COBOL applications that use SQL</a></strong><br />
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The following figures show the syntax for valid host structure array declarations.</li>
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<li class="ulchildlink"><strong><a href="rzajphostarrayindiccobol.htm">Host array indicator structure in COBOL applications that use SQL</a></strong><br />
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This figure shows the valid syntax for host structure array indicators.</li>
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</ul>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzajpcob.htm" title="This topic describes the unique application and coding requirements for embedding SQL statements in a COBOL program. Requirements for host structures and host variables are defined.">Code SQL statements in COBOL applications</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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