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Generate SQL query dynamically using the symbolic parameters
IBM Mainframe Forums -> DB2
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vnktrrd

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Joined: 12 Jan 2010
Posts: 34
Location: New York
PostPosted: Tue Aug 28, 2018 8:11 pm
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Hi,

I need help in achieving my requirement.
Thanks in advance.

I receive parms to JCL and based on that I have to prepare a SQL query which is to be run in the next step.

Input parms :

Input1
Input2
Input3

Select * from table1
Where table_field = Input1
and table_field = Input2
and table_field = Input3 ;

depending on what I receive in the Inputs the SQL query should be generated.
If there is no value in Input2 then the query should be like this

Select * from table1
Where table_field = Input1
and table_field = Input3 ;

Thanks,
Ramana.
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Arun Raj

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Joined: 17 Oct 2006
Posts: 2481
Location: @my desk
PostPosted: Tue Aug 28, 2018 10:30 pm
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Quote:
Select * from table1
Where table_field = Input1
and table_field = Input2
and table_field = Input3 ;
Are you sure it is 'and' and not 'or'?
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vnktrrd

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Joined: 12 Jan 2010
Posts: 34
Location: New York
PostPosted: Wed Aug 29, 2018 1:09 am
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It can be anything. I just gave an example with 'AND'. Does it make any difference ? All I want is to generate a query using the JCL parms.

Thanks,
Ramana.
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Nic Clouston

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Joined: 10 May 2007
Posts: 2455
Location: Hampshire, UK
PostPosted: Wed Aug 29, 2018 1:29 am
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Write your program then!
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Arun Raj

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PostPosted: Wed Aug 29, 2018 2:21 am
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Quote:
It can be anything. I just gave an example with 'AND'. Does it make any difference ?
Yes it might make a difference in your results. 'AND' does not make much sense in the context you showed. As far as building your sql dynamically, as Nic pointed out, you could choose any programming language of convenience, I'm sure there would be working examples in this forum. Post here if you come across any issues and someone would be around to help you. Good luck.
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RahulG31

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Joined: 20 Dec 2014
Posts: 446
Location: USA
PostPosted: Wed Aug 29, 2018 2:57 am
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If you are looking for any kind of SORT solution then you can probably make a use of PARM JPn. You can write something similar to:
Code:
//STEPSORT EXEC PGM=SORT,PARM='JP1"IN1",JP2"IN2",JP3"   "'
//SYSOUT   DD SYSOUT=*
//SYSPRINT DD SYSOUT=*
//SORTIN   DD *

/*
//SORTOUT DD SYSOUT=*
//SYSIN DD *
 OUTFIL IFTHEN=(WHEN=(1,3,CH,EQ,JP1),
        BUILD=(C'SELECT * FROM TABLE',/,C'WHERE TABLE_FIELD=',JP2,/,
               C'  AND TABLE_FIELD=',JP3)),
        IFTHEN=(WHEN=(1,3,CH,EQ,JP2),
        BUILD=(C'SELECT * FROM TABLE',/,C'WHERE TABLE_FIELD=',JP1,/,
               C'  AND TABLE_FIELD=',JP3)),
        IFTHEN=(WHEN=(1,3,CH,EQ,JP3),
        BUILD=(C'SELECT * FROM TABLE',/,C'WHERE TABLE_FIELD=',JP1,/,
               C'  AND TABLE_FIELD=',JP2))
 OPTION COPY
/*

SORTIN is having a blank line so that we can compare it with JPn values. I assumed all input fields have 3 byte length.

You can manipulate this logic according to your requirement.

.
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Rohit Umarjikar

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Joined: 21 Sep 2010
Posts: 3051
Location: NYC,USA
PostPosted: Wed Aug 29, 2018 3:25 am
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Instead of convoluted logic simply unload the table to a data set and use DFSORT include to play around The filter based on the input values
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Arun Raj

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Joined: 17 Oct 2006
Posts: 2481
Location: @my desk
PostPosted: Wed Aug 29, 2018 7:08 pm
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Here is another way of using the sort product (if you are at z/OS 2.1 or higher). Please note, I have included a dummy value at the end.
Code:
// EXPORT SYMLIST=(IN1,IN2,IN3)                       
// SET IN1='AAA',IN2='BBB',IN3='CCC'                 
//STEP01   EXEC  PGM=SORT                             
//SORTIN   DD *,SYMBOLS=JCLONLY                       
&IN1                                                 
&IN2                                                 
&IN3                                                 
//SYSIN    DD *                                       
  INCLUDE COND=(1,3,CH,NE,C' ')                       
  SORT FIELDS=COPY                                   
  OUTFIL REMOVECC,HEADER1=('SELECT * FROM TABLE',/,   
                           'WHERE TABLE_FIELD IN ( '),
                    BUILD=(C'''',1,3,C''',',80:X),   
                 TRAILER1=('''---'')')               
//SYSOUT   DD SYSOUT=*                               
//SORTOUT  DD SYSOUT=*                               
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