Remove Dups Trigger - SQL Server Forums

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Remove Dups Trigger

Author

Topic

jesus4u
Posting Yak Master

204 Posts

Posted - 2002-08-20 : 10:44:33

I have never written a trigger but is there a trigger that can detect on INSERT if dups are being written to the table? IF so can you please post a code example?

Thanks

jesus4u
Posting Yak Master

204 Posts

Posted - 2002-08-20 : 11:01:18

well what I did was check for existing records on the insert


	DECLARE @C int

	SELECT @C = count(*) FROM Responses WHERE Gid = @Gid AND msg = @msg AND Qid = @Qid AND ViewID = @ViewID  

	IF @C = 0

But is that an efficient way of doing things?

Thanks

LarsG
Constraint Violating Yak Guru

284 Posts

Posted - 2002-08-20 : 11:17:35

No, rather

if exists (select 1 from join table2 on table1.componentid = table2.componentID )
begin
-- code
end

Why can't you add a unique constraint to the table instead?

jesus4u
Posting Yak Master

204 Posts

Posted - 2002-08-20 : 11:26:29

quote:

No, rather

if exists (select 1 from join table2 on table1.componentid = table2.componentID )
begin
-- code
end

Why can't you add a unique constraint to the table instead?

Wouldn't it be


if NOT exists

unique constraint? Never heard of it.

LarsG
Constraint Violating Yak Guru

284 Posts

Posted - 2002-08-20 : 11:42:20

quote:

unique constraint? Never heard of it.

If you are going to use databases, it's about time. Lok it up in BOL or on this page

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/tsqlref/ts_ca-co_5t9v.asp

You can constraints to an existing table with an alter table statement.

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