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

Sample MERGE statement in this case would be:

MERGE INTO Table1 t1
USING (SELECT 'SomeValue' as Column_id FROM dual) t2 ON
(t1.column_id = t2.column_id)
WHEN MATCHED THEN
    UPDATE SET(...)
WHEN NOT MATCHED THEN
    INSERT (t1.column_id)
    VALUES ('SomeValue');