I used to write my EXISTS checks like this:
IF EXISTS (SELECT * FROM TABLE WHERE Columns=@Filters)
BEGIN
UPDATE TABLE SET ColumnsX=ValuesX WHERE Where Columns=@Filters
END
One of the DBA's in a previous life told me that when I do an EXISTS clause, use SELECT 1 instead of SELECT *
IF EXISTS (SELECT 1 FROM TABLE WHERE Columns=@Filters)
BEGIN
UPDATE TABLE SET ColumnsX=ValuesX WHERE Columns=@Filters
END
Does this really make a difference?