Sorry, I guess I could have been a little more clear. Another example:
Table Employee: Emp_id number primary key -- generated with a sequence Emp_name varchar2(20) unique Table Employee_log: Emp_id number primary key Time_stamp date primary key Emp_stats varchar2(50) A process receives the employee name, and other information that needs to be stored in the table employee_log. The process needs to retrieve the emp_id from the employee table, so it does a lookup. If the employee exists, the emp_id is retrieved and the information is then inserted into the employee_log table. If the employee does not currently exist, a new employee is added to the table employee. We run into problems when we have many concurrent processes running and more than one process receives the same employee name. They both do a lookup and they both conclude the employee does not exist. Thus, they both try and do an insert into the employee table. One will succeed and the other will fail. Is there away to avoid this scenario? I hope I made this a little clearer. Thanks, Rick Stephenson -----Original Message----- Sent: Monday, February 24, 2003 1:05 PM To: Multiple recipients of list ORACLE-L 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. [EMAIL PROTECTED] -----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 This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to which they are addressed. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this e-mail by mistake and delete this e-mail from your system. If you are not the intended recipient you are notified that disclosing, copying, forwarding or otherwise distributing or taking any action in reliance on the contents of this information is strictly prohibited. -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: DENNIS WILLIAMS INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to which they are addressed. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this e-mail by mistake and delete this e-mail from your system. If you are not the intended recipient you are notified that disclosing, copying, forwarding or otherwise distributing or taking any action in reliance on the contents of this information is strictly prohibited. -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Rick Stephenson INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
