Apologies I probably didn't make my self clear, the query wasn't hanging but was taking an age to execute to the point i would stop the query.

I think it was because it was trying to delete everything in my target table that didn't have a match to the source.

After creating my target table using a CTE

WITH k_target AS

(

SELECT *

FROM Kart

WHERE sessionid = @sessionid

)

MERGE k_target

it worked but not as expected. It deleted everything that wasn't in my source for that sessionid. However the other records for that sessionid I want to keep as they are not of offer_type 'GWP'.