Oracle-L: RE: SQL question

From: DENNIS WILLIAMS <DWILLIAMS_at_LIFETOUCH.COM>
Date: Mon, 24 Feb 2003 12:05:02 -0800
Message-ID: <F001.00557456.20030224120502@fatcity.com>

Rick - What about selecting the primary key for your table from a sequence? Oracle will ensure each session receives a unique number.

What is your overall goal?

Dennis Williams
DBA, 40%OCP, 100% DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----
Sent: Monday, February 24, 2003 1:50 PM
To: Multiple recipients of list ORACLE-L

OS: Solaris 2.8

Database: Oracle 9.2.0.2

Situation in chronological order

Connection A: select * from table A where id = 1; Result: no rows returned
-- This means I need to insert the row, as it does not exists yet.

Connection B: select * from table A where id = 1; Result: no rows returned
-- This means I need to insert the row, as it does not exists yet.

Connection A: insert into table A(id) values = 1; Result: 1 row inserted

Connection B: insert into table A(id) values = 1; Result: Unique constraint violated -- This is the problem. How do I avoid this happening?

Question: How can I force connection B to wait for connection A to insert the new row before it does the select?

If I were updating the row, I could use the "for update" clause to force the wait. Is there a clean way to do that for an insert?

Thanks for your help,

Rick Stephenson

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Author: DENNIS WILLIAMS
INET: DWILLIAMS_at_LIFETOUCH.COM

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