Question

I have a process that I do not want to track if something is a create or an update. Tracking would be complex. I would like to perform a create OR update. The schema is like…

col1 varchar() (PK)
col2 varchar() (PK)
col3 varchar() (PK)
col4 varchar()

I am thinking about doing

TRY
{
    INSERT ...
}
CATCH(DuplicateKeyException)
{
    UPDATE ...
}

What do you suggest?

---

I want to ensure that I understand the other top voted answer. Given my schema, the UPDATE always occurs (even with an INSERT), but the insert only occurs where it does not exist?

 //UPSERT
INSERT INTO [table]
SELECT [col1] = @col1, [col2] = @col2, [col3] = @col3, [col4] = @col4
FROM [table]
WHERE NOT EXISTS (
    -- race condition risk here?
    SELECT  1 
    FROM [table] 
    WHERE [col1] = @col1 
        AND [col2] = @col2
        AND [col3] = @col3
)

UPDATE [table]
SET [col4] = @col4
WHERE [col1] = @col1 
    AND [col2] = @col2
    AND [col3] = @col3

Answer 1

update table1 set col1=1,col2=2,col3=3 where a=1
if @@ROWCOUNT=0
   insert into table1 (col1,col2,col3) values (1,2,3)

I think its quicker than checking existance first.