Procedure to compare 2 Tupels

Question

Hi,
I´m new in the Procedure-Topic and need some help.
At the moment there is a Scheduled Job running. This DB-Job does a Insert from Table A to Table B every two hours.
The problem is, that only records from Table A should be inserted to Table B if this record/s is/are not inserted in Table A, yet.
If the Record isn´t in Table B, it need to be inserted there.
If the Record is in Table B yet, it must not be inserted in Table B.
Thank you for your help
Best Regards
Steve

Answer 1

Hi,
That sounds like a job for MERGE, rather than INSERT. If you're using Oracle 10 (or higher), then simply omit the WHEN MATCHED clause.
You could also put a unique constraint on the table. If you try to insert a row that's already in the table; the statement will fail. (If you're only adding 1 row at a time, then the only INSERTs you lose will be the ones you want to lose.)
Personally, I would do both: use MERGE to only add rows when they really are new, and use a unique constraint to raise an error (and block the bad data) if the MERGE doesn't work correctly.
I hope this answers your question.
If not, post a little sample data (CREATE TABLE and INSERT statements, relevant columns only) for all tables involved, and also post the results you want from that data.
If you're asking about a DML statement, such as INSERT, the sample data will be the contents of the table(s) before the DML, and the results will be state of the changed table(s) when everything is finished.
Explain, using specific examples, how you get those results from that data.
Always say which version of Oracle you're using.
Edited by: Frank Kulash on Feb 6, 2012 8:53 AM