159 lines
8.5 KiB
HTML
159 lines
8.5 KiB
HTML
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<meta name="DC.Title" content="Indicator variables and stored procedures" />
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<meta name="abstract" content="Indicator variables can be used with the CALL statement, provided host variables are used for the parameters, to pass additional information to and from the procedure." />
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<meta name="description" content="Indicator variables can be used with the CALL statement, provided host variables are used for the parameters, to pass additional information to and from the procedure." />
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<meta name="DC.subject" content="stored procedures, parameter passing, indicator variables, stored procedures, indicator variables" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Indicator variables and stored procedures</title>
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</head>
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<body id="rbafyindicator"><a name="rbafyindicator"><!-- --></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">Indicator variables and stored procedures</h1>
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<div><p>Indicator variables can be used with the CALL statement, provided
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host variables are used for the parameters, to pass additional information
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to and from the procedure. </p>
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<div class="section"><p>Indicator variables are the SQL standard means of denoting that
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the associated host variable should be interpreted as containing the null
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value, and this is their primary use.</p>
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</div>
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<div class="section"><p>To indicate that an associated host variable contains the null
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value, the indicator variable, which is a two-byte integer, is set to a negative
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value. A CALL statement with indicator variables is processed as follows:
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</p>
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<ul><li>If the indicator variable is negative, this denotes the null value. A
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default value is passed for the associated host variable on the CALL and the
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indicator variable is passed unchanged.</li>
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<li>If the indicator variable is not negative, this denotes that the host
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variable contains a non-null value. In this case, the host variable and the
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indicator variable are passed unchanged.</li>
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</ul>
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</div>
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<div class="section"><p>These rules of processing are the same for input parameters to
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the procedure as well as output parameters returned from the procedure. When
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indicator variables are used with stored procedures, the correct method of
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coding their handling is to check the value of the indicator variable first
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before using the associated host variable.</p>
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</div>
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<div class="section"><p>The following example illustrates the handling of indicator variables
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in CALL statements. Notice that the logic checks the value of the indicator
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variable before using the associated variable. Also note the method that the
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indicator variables are passed into procedure PROC1 (as a third argument consisting
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of an array of two-byte values).</p>
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</div>
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<div class="section"><div class="note"><span class="notetitle">Note:</span> By using the code examples, you agree to the terms of the <a href="codedisclaimer.htm">Code license and disclaimer information</a>.</div>
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<p>Assume a procedure was defined
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as follows:</p>
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</div>
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<div class="example"> <pre> <strong>CREATE PROCEDURE</strong> PROC1
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(<strong>INOUT</strong> DECIMALOUT <strong>DECIMAL</strong>(7,2), <strong>INOUT</strong> DECOUT2 <strong>DECIMAL</strong>(7,2))
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<strong>EXTERNAL NAME</strong> LIB1.PROC1 <strong>LANGUAGE RPGLE</strong>
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<strong>GENERAL WITH NULLS</strong>)
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</pre>
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</div>
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<div class="example"> <p><strong>Handling of indicator variables in CALL statements</strong></p>
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<pre>++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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Program CRPG
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++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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D INOUT1 S 7P 2
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D INOUT1IND S 4B 0
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D INOUT2 S 7P 2
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D INOUT2IND S 4B 0
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C EVAL INOUT1 = 1
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C EVAL INOUT1IND = 0
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C EVAL INOUT2 = 1
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C EVAL INOUT2IND = -2
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C/EXEC SQL CALL PROC1 (:INOUT1 :INOUT1IND , :INOUT2
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C+ :INOUT2IND)
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C/END-EXEC
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C EVAL INOUT1 = 1
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C EVAL INOUT1IND = 0
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C EVAL INOUT2 = 1
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C EVAL INOUT2IND = -2
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C/EXEC SQL CALL PROC1 (:INOUT1 :INOUT1IND , :INOUT2
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C+ :INOUT2IND)
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C/END-EXEC
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C INOUT1IND IFLT 0
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C* :
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C* HANDLE NULL INDICATOR
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C* :
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C ELSE
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C* :
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C* INOUT1 CONTAINS VALID DATA
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C* :
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C ENDIF
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C* :
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C* HANDLE ALL OTHER PARAMETERS
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C* IN A SIMILAR FASHION
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C* :
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C RETURN
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++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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End of PROGRAM CRPG
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++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++</pre>
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<pre>++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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Program PROC1
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++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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D INOUTP S 7P 2
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D INOUTP2 S 7P 2
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D NULLARRAY S 4B 0 DIM(2)
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C *ENTRY PLIST
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C PARM INOUTP
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C PARM INOUTP2
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C PARM NULLARRAY
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C NULLARRAY(1) IFLT 0
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C* :
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C* INOUTP DOES NOT CONTAIN MEANINGFUL DATA
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C*
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C ELSE
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C* :
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C* INOUTP CONTAINS MEANINGFUL DATA
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C* :
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C ENDIF
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C* PROCESS ALL REMAINING VARIABLES
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C*
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C* BEFORE RETURNING, SET OUTPUT VALUE FOR FIRST
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C* PARAMETER AND SET THE INDICATOR TO A NON-NEGATIV
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C* VALUE SO THAT THE DATA IS RETURNED TO THE CALLING
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C* PROGRAM
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C*
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C EVAL INOUTP2 = 20.5
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C EVAL NULLARRAY(2) = 0
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C*
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C* INDICATE THAT THE SECOND PARAMETER IS TO CONTAIN
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C* THE NULL VALUE UPON RETURN. THERE IS NO POINT
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C* IN SETTING THE VALUE IN INOUTP SINCE IT WON'T BE
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C* PASSED BACK TO THE CALLER.
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C EVAL NULLARRAY(1) = -5
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C RETURN
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++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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End of PROGRAM PROC1
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++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++</pre>
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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="rbafysproeg.htm" title="A procedure (often called a stored procedure) is a program that can be called to perform operations that can include both host language statements and SQL statements. Procedures in SQL provide the same benefits as procedures in a host language.">Stored procedures</a></div>
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</div>
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</div>
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</body>
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