Můžete to udělat pomocí OR:
SELECT * FROM Person WHERE Status = @Status OR @Status IS NULL
Nebo UNION ALL:
SELECT * FROM Person WHERE Status = @Status
UNION ALL
SELECT * FROM Person WHERE @Status IS NULL
Můžete to udělat pomocí OR:
SELECT * FROM Person WHERE Status = @Status OR @Status IS NULL
Nebo UNION ALL:
SELECT * FROM Person WHERE Status = @Status
UNION ALL
SELECT * FROM Person WHERE @Status IS NULL