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Hello...
Babu Suresh <SureshB@alfuttaim.co.ae> wrote:
>
> >
> > Dear all,
> >
> > Thanks for the response and solutions provided to me for my earli
> > query about OPNQRYF.
> >
> > Now I need the help in using triggers.
> >
> > I know that triggers are the programs which can be made to get
> > executed when a record is inserted or updated or deleted from a
> file. My
> > requirement is to find a value of a partcular field in that record
> which
> > has just been Written/Updated. How to achieve this with the help o
> > trigger. If there is any other way please suggest.
> >
> >
> > Thank you.
> > P.Sureshbabu
> > DSQ Software Ltd.
> > Chennai.
> > India.
The way that I like to do triggers is to create an externally
defined data structure, using the layout of the file that your
trigger is on.
If that external DS is based on a pointer, you can then set it to
point to the area of memory that the record buffer is in, based
on the offset in the trigger structure...
like so:
D AFTER C CONST('1')
D BEFORE C CONST('2')
D INSERT C CONST('1')
D DELETE C CONST('2')
D UPDATE C CONST('3')
D dsBefore e ds EXTNAME(MYFILE)
D BASED(p_Before)
D PREFIX(dsB_)
D p_Before S *
D dsAfter e ds EXTNAME(MYFILE)
D BASED(p_After)
D PREFIX(dsA_)
D p_After S *
D dsTrg ds
D dsTrgBuff 1 3072A DIM(3072)
D dsTrgFile 1 10A
D dsTrgLib 11 20A
D dsTrgMbr 21 30A
D dsTrgEvent 31 31A
D dsTrgTime 32 32A
D dsTrgCmtLk 33 33A
D dsTrgFill1 34 36A
D dsTrgCSID 37 40I 0
D dsTrgFill2 41 48A
D dsTrgBOff 49 52I 0
D dsTrgBLen 53 56I 0
D dsTrgBNOff 57 60I 0
D dsTrgBNLen 61 64I 0
D dsTrgAOff 65 68I 0
D dsTrgALen 69 72I 0
D dsTrgANOff 73 76I 0
D dsTrgANLen 77 80I 0
D dsTrgFill3 81 96A
D peLength S 10I 0
C *ENTRY PLIST
C PARM dsTrg
c parm peLength
c Select
c when dsTrgEvent = UPDATE
c eval p_Before = %addr(dsTrgBuff(dsTrgBOff+1))
c eval p_After = %addr(dsTrgBuff(dsTrgAOff+1))
c exsr RecUpdated
c when dsTrgEvent = INSERT
c eval p_After = %addr(dsTrgBuff(dsTrgAOff+1))
c exsr RecWritten
c when dsTrgEvent = DELETE
c eval p_Before = %addr(dsTrgBuff(dsTrgBOff+1))
c exsr RecDeleted
c Endsl
C return
CSR RecUpdated begsr
C*
C* ... code goes here to deal with an updated record ...
C*
C* You can use dsB_(fldname) to see what the data was
C* BEFORE the update, and dsA_(fldname) to see what
C* the data will be AFTER the update.
C*
C* example: if your external name is CUST, then:
C* dsB_CUST is the field before the update
C* dsA_CUST is the field after the update.
C*
CSR endsr
CSR RecWritten begsr
C*
C* ... code goes here to handle when a new record is added ...
C*
C* Because there is no prior data for this record in the
C* file, you can only use the "AFTER" fields from the
C* data structure.
C*
C* example: if the external name is CUST, then:
C* dsA_CUST is what the field will be after the write.
C*
CSR endsr
CSR RecDeleted begsr
C*
C* ...Code goes here for deleted records...
C*
C* Use dsB_ to check what the rec is before its deleted...
C*
CSR endsr
>
> Dear all,
>
> One more addition to my below query:
> If that particular record is written/updated by an RPG or CLP, Is i
> possible to know what is the name of the program?
>
> Expecting help.
>
> Thanks
> P.Sureshbabu
> DSQ Software ltd.
> Madras,
> India.
>
You should be able to determine the name of the RPG that updated
the file -- but CL programs cant update/add records, so that's
not a huge issue :)
Retrieving the program name is a bit more difficult. The only
way I know how to do this is to send a message back to the previous
program in your call stack, then receive that same message (from
the previous program's queue) and determine what program it was
sent to.
I'd strongly encourage you to NOT do this in a trigger. It will
slow down your file updates. If you REALLY want to do it, however,
let me know and I'll send an example of doing this to you.
Hope that helps...
Scott Klement
Information Systems Manager
Klement's Sausage Co, Inc.
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