Only inserting a row if it's not already there

Question

I had always used something similar to the following to achieve it:

INSERT INTO TheTable
SELECT
    @primaryKey,
    @value1,
    @value2
WHERE
    NOT EXIST         


        

Answer 1

You could use MERGE:

MERGE INTO Target
USING (VALUES (@primaryKey, @value1, @value2)) Source (key, value1, value2)
ON Target.key = Source.key
WHEN MATCHED THEN
    UPDATE SET value1 = Source.value1, value2 = Source.value2
WHEN NOT MATCHED BY TARGET THEN
    INSERT (Name, ReasonType) VALUES (@primaryKey, @value1, @value2)