Danger of using 'IF EXISTS… UPDATE .. ELSE .. INSERT' and what is the alternative?

Question

This question is related with Occasionally Getting SqlException: Timeout expired. Actually, I am using IF EXISTS... UPDATE .. ELSE .. INSERT heavily in my app.

Answer 1

Merge, is in the first case created to compare 2 tables, so if that is the case you could use merge.

Take a look at the following, which is also another option.

In this case unfortunately you have the possibility of getting a problem with concurrency.

--Just update a row 
UPDATE Table1 SET (...) WHERE Column1='SomeValue'
   -- If 0 rows are updated ...
  IF @@ROWCOUNT=0
--Insert Row
INSERT INTO Table1 VALUES (...)

In this blog its explained more.

Additionally this interesting blog is about concurrency.