Must not redefine DB field in subproc

This issue may have already arisen previously but it has caused me such
a significant problem that I wish to mention it.



The code snippet below can demonstrate the problem I made for myself by
inadvertently having a field named SEQ_NO defined locally within a
sub-procedure while the same field also exists as a column in a file
read by the same sub-procedure.



The process was initially written to use a field named SEQ_NO defined
locally.

Then it was augmented to retrieve the SEQ_NO from the most recent SEQ_NO
column used on a file.

So the process needs to know the last sequence number on a file keyed by
FILE_NO/SEQ_NO.

I took a while to realize that the sub-procedure does not populate the
value of SEQ_NO from the file when it has also been defined locally.

The code seemed innocuous until used in a production run when duplicate
key errors began to arise because the SEQ_NO was not being incremented
correctly.



H DftActGrp(*No) Option(*NoDebugIO : *SrcStmt )

FTBLCA_DF IF E K DISK RENAME(TBLCA_DF:DFREC)



D procfile PR



/free

FILE_NO = 1200001;

procfile();

*inLR = *on;

Return;

/end-free



P procfile B



D SEQ_NO S 4 0



/free

// Retrieve last sequence no used for this FILE_NO

Setgt (FILE_NO) TBLCA_DF;

Readpe (FILE_NO) TBLCA_DF;

If %EOF;

SEQ_NO = 0; // If no masterfile then set to zero

Endif;

Dsply ('Last sequence no. is ' + %editC(SEQ_NO:'Z'));



/end-free

P E



Cheers, Peter


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