SQL Server Subquery returned more than 1 value. This is not permitted when the subquery follows (chars) or when the subquery is used as an expression

Question

I am trying to update some fields based on their occurence. If they only occur one time, I am updating some status field.

My current code is as follows:

Answer 1

Use IN keyword instead of equals operator like so:

UPDATE table1
SET statusField = 1
WHERE someID IN (
           SELECT someID
           FROM table1
           GROUP BY someID HAVING COUNT(*) = 1
           )

Using = requires that exactly 1 result is returned by the subquery. IN keyword works on a list.