191 lines
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HTML
191 lines
11 KiB
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<meta name="DC.Title" content="SQLDA format" />
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<meta name="abstract" content="The SQLDA consists of four variables followed by an arbitrary number of occurrences of a sequence of six variables collectively named SQLVAR." />
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<meta name="DC.subject" content="SQLDA (SQL descriptor area), format, dynamic SQL, SQLDA (SQL descriptor area) format, SQLDAID, SQLDABC, SQLN, SQLD, SQLVAR, SQLTYPE, SQLLEN, SQLRES, SQLDATA, SQLIND, SQLNAME, SQLVAR2, SQLLONGLEN, SQLDATALEN, SQLDATATYPE_NAME" />
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<meta name="keywords" content="SQLDA (SQL descriptor area), format, dynamic SQL, SQLDA (SQL descriptor area) format, SQLDAID, SQLDABC, SQLN, SQLD, SQLVAR, SQLTYPE, SQLLEN, SQLRES, SQLDATA, SQLIND, SQLNAME, SQLVAR2, SQLLONGLEN, SQLDATALEN, SQLDATATYPE_NAME" />
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<title>SQLDA format</title>
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</head>
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<body id="rbafysqldaformat"><a name="rbafysqldaformat"><!-- --></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">SQLDA format</h1>
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<div><p>The SQLDA consists of four variables followed by an arbitrary number
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of occurrences of a sequence of six variables collectively named SQLVAR.</p>
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<div class="section"><div class="note"><span class="notetitle">Note:</span> The SQLDA in REXX is different. </div>
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<p>When an SQLDA is used in OPEN, FETCH, CALL, and EXECUTE, each occurrence
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of SQLVAR describes a host variable.</p>
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</div>
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<div class="section"><p>The fields of the SQLDA are as follows:</p>
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<dl><dt class="dlterm">SQLDAID</dt>
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<dd>SQLDAID is as used an 'eyecatcher" for storage dumps. It is a string of
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8 characters that have the value <samp class="codeph">'</samp>SQLDA<samp class="codeph">'</samp> after
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the SQLDA is used in a PREPARE or DESCRIBE statement. This variable is not
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used for FETCH, OPEN, CALL, or EXECUTE. <p>Byte 7 can be used to determine
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if more than one SQLVAR entry is needed for each column. Multiple SQLVAR entries
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may be needed if there are any LOB or distinct type columns. This flag is
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set to a blank if there are not any LOBs or distinct types.</p>
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<p>SQLDAID
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is not applicable in REXX.</p>
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</dd>
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<dt class="dlterm">SQLDABC</dt>
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<dd>SQLDABC indicates the length of the SQLDA. It is a 4-byte integer that
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has the value SQLN*LENGTH(SQLVAR) + 16 after the SQLDA is used in a PREPARE
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or DESCRIBE statement. SQLDABC must have a value equal to or greater than
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SQLN*LENGTH(SQLVAR) + 16 before it is used by FETCH, OPEN, CALL, or EXECUTE.
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<p>SQLABC is not applicable in REXX.</p>
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</dd>
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<dt class="dlterm">SQLN</dt>
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<dd>SQLN is a 2-byte integer that specifies the total number of occurrences
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of SQLVAR. It must be set before being used by any SQL statement to a value
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greater than or equal to 0. <p>SQLN is not applicable in REXX.</p>
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</dd>
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<dt class="dlterm">SQLD</dt>
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<dd>SQLD is a 2-byte integer that specifies the number of occurrences of SQLVAR,
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in other words, the number of host variables or columns described by the SQLDA.
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This field is set by SQL on a DESCRIBE or PREPARE statement. In other statements,
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this field must be set before being used to a value greater than or equal
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to 0 and less than or equal to SQLN.</dd>
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<dt class="dlterm">SQLVAR</dt>
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<dd>This group of values are repeated once for each host variable or column.
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These variables are set by SQL on a DESCRIBE or PREPARE statement. In other
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statements, they must be set before being used. These variables are defined
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as follows: <dl><dt class="dlterm">SQLTYPE</dt>
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<dd>SQLTYPE is a 2-byte integer that specifies the data type
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of the host variable or column. See <a href="../db2/rbafzmstsqltc.htm#sqltc">SQLTYPE
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and SQLLEN</a> for a table of the valid values.
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Odd values for SQLTYPE show that the host variable has an associated indicator
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variable addressed by SQLIND.</dd>
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<dt class="dlterm">SQLLEN</dt>
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<dd>SQLLEN is a 2-byte integer variable that specifies the length attribute
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of the host variable or column.</dd>
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<dt class="dlterm">SQLRES</dt>
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<dd>SQLRES is a 12-byte reserved area for boundary alignment purposes. Note
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that, in <span class="keyword">i5/OS™</span>, pointers <em>must</em> be
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on a quad-word boundary. <p>SQLRES is not applicable in REXX.</p>
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</dd>
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<dt class="dlterm">SQLDATA</dt>
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<dd>SQLDATA is a 16-byte pointer variable that specifies the address of the
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host variables when the SQLDA is used on OPEN, FETCH, CALL, and EXECUTE. <p>When
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the SQLDA is used on PREPARE and DESCRIBE, this area is overlaid with the
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following information:</p>
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<p>The CCSID of a character or graphic field is
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stored in the third and fourth bytes of SQLDATA. For BIT data, the CCSID is
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65535. In REXX, the CCSID is returned in the variable SQLCCSID.</p>
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</dd>
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<dt class="dlterm">SQLIND</dt>
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<dd>SQLIND is a 16-byte pointer that specifies the address of a small integer
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host variable that is used as an indication of null or not null when the SQLDA
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is used on OPEN, FETCH, CALL, and EXECUTE. A negative value indicates null
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and a non-negative indicates not null. This pointer is only used if SQLTYPE
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contains an odd value. <p>When the SQLDA is used on PREPARE and DESCRIBE,
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this area is reserved for future use.</p>
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</dd>
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<dt class="dlterm">SQLNAME</dt>
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<dd>SQLNAME is a variable-length character variable with a maximum length
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of 30. After a PREPARE or DESCRIBE, this variable contains the name of selected
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column, label, or system column name. In OPEN, FETCH, EXECUTE, or CALL, this
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variable can be used to pass the CCSID of character strings. CCSIDs can be
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passed for character and graphic host variables. <p>The SQLNAME
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field in an SQLVAR array entry of an input SQLDA can be set to specify the
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CCSID. See <a href="../db2/rbafzmstsname.htm#sname">CCSID
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values in SQLDATA or SQLNAME</a> for the layout of the CCSID data in this
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field.</p>
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<div class="note"><span class="notetitle">Note:</span> It is important to remember that the SQLNAME field is only
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for overriding the CCSID. Applications that use the defaults do not need to
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pass CCSID information. If a CCSID is not passed, the default CCSID for the
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job is used.</div>
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<p>The default for graphic host variables is the associated
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double-byte CCSID for the job CCSID. If an associated double-byte CCSID does
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not exist, 65535 is used.</p>
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</dd>
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</dl>
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</dd>
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</dl>
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</div>
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<div class="section"> <dl><dt class="dlterm">SQLVAR2</dt>
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<dd>This is the Extended SQLVAR structure that contains 3 fields. Extended
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SQLVARs are needed for all columns of the result if the result includes any
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distinct type or LOB columns. For distinct types, they contain the distinct
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type name. For LOBs, they contain the length attribute of the host variable
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and a pointer to the buffer that contains the actual length. If locators
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are used to represent LOBs, these entries are not necessary. The number of
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Extended SQLVAR occurrences needed depends on the statement that the SQLDA
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was provided for and the data types of the columns or parameters being described.
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Byte 7 of SQLDAID is always set to the number of sets of SQLVARs necessary. <p>If
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SQLD is not set to a sufficient number of SQLVAR occurrences: </p>
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<ul><li>SQLD is set to the total number of SQLVAR occurrences needed for all sets.</li>
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<li>A +237 warning is returned in the SQLCODE field of the SQLCA if at least
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enough were specified for the Base SQLVAR Entries. The Base SQLVAR entries
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are returned, but no Extended SQLVARs are returned.</li>
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<li>A +239 warning is returned in the SQLCODE field of the SQLCA if enough
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SQLVARs were not specified for even the Base SQLVAR Entries. No SQLVAR entries
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are returned.</li>
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</ul>
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<dl><dt class="dlterm">SQLLONGLEN</dt>
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<dd>SQLLONGLEN is a 4-byte integer variable that specifies the length attribute
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of a LOB (BLOB, CLOB, or DBCLOB) host variable or column.</dd>
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<dt class="dlterm">SQLDATALEN</dt>
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<dd>SQLDATALEN is a 16-byte pointer variable that specifies the address of
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the length of the host variable. This variable is used for LOB (BLOB, CLOB,
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and DBCLOB) host variables only. It is not used for DESCRIBE or PREPARE. <p>If
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this field is NULL, then the actual length of the data is stored in the 4
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bytes immediately before the start of the data, and SQLDATA points to the
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first byte of the field length. The length indicates the number of bytes for
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a BLOB or CLOB, and the number of characters for a DBCLOB.</p>
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<p>If this field
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is not NULL, it contains a pointer to a 4-byte long buffer that contains the
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actual length in bytes (even for DBCLOB) of the data in the buffer pointed
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to by the SQLDATA field in the matching base SQLVAR.</p>
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</dd>
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<dt class="dlterm">SQLDATATYPE_NAME</dt>
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<dd>SQLDATATYPE_NAME is a variable-length character variable with a maximum
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length of 30. It is only used for DESCRIBE or PREPARE. This variable is set
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to one of the following: <ul><li>For a distinct type column, the database manager sets this to the fully
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qualified distinct type name. If the qualified name is longer than 30 bytes,
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it is truncated.</li>
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<li>For a label, the database manager sets this to the first 20 bytes of the
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label. </li>
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<li>For a column name, the database manager sets this to the column name.</li>
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</ul>
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</dd>
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</dl>
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</dd>
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</dl>
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</div>
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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="rbafyprocesssqlda.htm" title="There are two basic types of SELECT statements: fixed list and varying list.">Process SELECT statements and use a descriptor</a></div>
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</div>
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<div class="relref"><strong>Related reference</strong><br />
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<div><a href="rbafydynexample.htm" title="Suppose your application needs to be able to handle a dynamic SELECT statement, one that changes from one use to the next. This statement can be read from a display, passed in from another application, or built dynamically by your application.">Example: Select-statement for allocating storage for SQLDA</a></div>
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</div>
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<div class="relinfo"><strong>Related information</strong><br />
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<div><a href="../rzajp/rzajprexx.htm">Coding SQL statements in REXX Applications</a></div>
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</div>
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</div>
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</body>
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