On Tue, 2006-04-11 at 00:43, v.suryaprabha@xxxxxxxxx wrote: > Hi > Now we cannot change the field type. Because already our application > is running and thousands of records are already entered. we are getting > same no for clipid when 2 users are entering data at a time. so how to > solve the problem Addendum: Note that you can also set the default for the clipid column to be the nextval('sequencename') at the same time, then if anyone DOES insert a row without getting the nextval() first, it'll still give them the proper value. Note that a "serial" type is actually just an int with a default and a dependency. Also, you really should have a primary key or unique index with not null attribute on the clipid column as well, just to be safe. PK is about the same as unique & not null, just that foreign references aren't automatic, but I get the feeling foreign keys aren't playing a role in your schema just now.