101 lines
5.9 KiB
HTML
101 lines
5.9 KiB
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<title>Use arrays of host structures in C and C++ applications that use SQL</title>
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</head>
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<body id="rzajphostarrayc"><a name="rzajphostarrayc"><!-- --></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 arrays of host structures in C and C++ applications that use SQL</h1>
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<div><p>In C and C++ programs, you can define a host structure array that
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has the dimension attribute. Host structure arrays have a maximum of two levels,
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even though the array might occur within a multiple-level structure. Another
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structure is not needed if a varying-length character string or a varying-length
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graphic string is not used.</p>
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<div class="section"><p>In this C example, </p>
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<pre>struct {
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_Packed struct{
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char c1_var[20];
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short c2_var;
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} b_array[10];
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} a_struct;
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</pre>
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</div>
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<div class="section"><p>and in this C++ example, </p>
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<pre>#pragma pack(1)
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struct {
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struct{
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char c1_var[20];
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short c2_var;
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} b_array[10];
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} a_struct;
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#pragma pack()</pre>
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<p>the following are true: </p>
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<ul><li>All of the members in b_array must be valid variable declarations.</li>
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<li>The _Packed attribute must be specified for the struct tag.</li>
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<li>b_array is the name of an array of host structures containing the members
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c1_var and c2_var.</li>
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<li>b_array may only be used on the blocked forms of FETCH statements and
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INSERT statements.</li>
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<li>c1_var and c2_var are not valid host variables in any SQL statement.</li>
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<li>A structure cannot contain an intermediate level structure.</li>
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</ul>
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<p> For example, in C you can retrieve 10 rows from the cursor with: </p>
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<pre>_Packed struct {char first_initial;
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char middle_initial;
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_Packed struct {short lastname_len;
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char lastname_data[15];
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} lastname;
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double total_salary;
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} employee_rec[10];
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struct { short inds[4];
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} employee_inds[10];
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…
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EXEC SQL <strong>DECLARE</strong> C1 <strong>CURSOR</strong> FOR
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<strong>SELECT SUBSTR</strong>(FIRSTNME,1,1), MIDINIT, LASTNAME,
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SALARY+BONUS+COMM
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<strong>FROM</strong> CORPDATA.EMPLOYEE;
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EXEC SQL <strong>OPEN</strong> C1;
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EXEC SQL <strong>FETCH</strong> C1 <strong>FOR</strong> 10 <strong>ROWS INTO</strong> :employee_rec:employee_inds;
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…</pre>
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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="rzajphoststrucarrayc.htm">Host structure array in C and C++ applications that use SQL</a></strong><br />
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The following figure shows the valid syntax for host structure array declarations.</li>
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<li class="ulchildlink"><strong><a href="rzajphoststrucindicatorc.htm">Host structure array indicator structure in C and C++ applications that use SQL</a></strong><br />
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The figure shows the valid syntax for host structure array indicator structure declarations.</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="rzajpc.htm" title="This topic describes the unique application and coding requirements for embedding SQL statements in a C or C++ program.">Code SQL statements in C and C++ 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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