Duplicate Check in COBOL

zack786 · New User Joined: 22 May 2007 Posts: 3 Location: New York

Need help. I am reading a SYSIN PDS member file and loading a fixed length (80 bytes) table with 100 entries. But I need to check the SYSIN member to make sure there are no duplicate entries, before I load it to the table in memory.

What is the best way to accomplaish DUP CHECKING in COBOL. Thanks.

William Thompson · Posted: Thu May 24, 2007 5:04 am

Is the input sorted? Without it being sorted, you will need a 100 byte internal table, but if you are building a table, just scan prior to inserting.....

zack786 · New User Joined: 22 May 2007 Posts: 3 Location: New York

No the input is not sorted. How do I scan prior to loading ? BINARY SEARCH ?

dick scherrer · Posted: Thu May 24, 2007 5:28 am

Hello,

Read the external file, look in the table to see if the value is already there, if it is, skip that entry (if you're ignoring dups), as each value from the external file is read, it is loaded into the "next" available position in the table as long as it is not a duplicate.

I'd suggest making sure the external file is sorted before you build and use the table.

zack786 · New User Joined: 22 May 2007 Posts: 3 Location: New York

Thanks for your reply. OK I am sorry if I did not make myself clear. The table that I load table into memory stays in memory for the duration of the time-period that the job is up and running. The allocated memory block is cleared when the job comes down. Then again, I do the load (read sysin, check for dups, load into memory) when the job is submitted.

dick scherrer · Posted: Thu May 24, 2007 6:22 am

You're welcome.

Yes, i believe i understood that the external file would be read, loaded into the internal table, and be available for the duration of the run.

What i'm not sure of is whether you have what you need to proceed or if there remain any questions.

Phrzby Phil · Posted: Thu May 24, 2007 5:59 pm

Why not sort first and let the sort eliminate key dupes using "SUM FIELDS=NONE"?

p_gandhi · Posted: Mon May 28, 2007 6:21 pm

I had the same kind of projects where I hae to eliminate the duplicates from the DB2 table, what I did as follows

1) Sort the file by keys
2) read the file
in main process

when keys not = previous keys
write to output file

read next

this way you writing file when keys are not same and when the keys are same or not you reading next and move the previous key to WS for comparing

Raphael Bacay · Posted: Wed May 30, 2007 9:20 am

That idea by Phrzby Phil looks like an efficient solution to your problem.