Anda harus memberikan nilai Combobox di @Status
:
Di sini Anda perlu mengatur kondisi seperti ini:
DECLARE @Status varchar(15)
--set the Status
SELECT *
FROM tbl_Location
WHERE (@Status = 'All'
OR (@Status = 'Nulls' AND YEAR IS NULL)
OR (@Status = 'Not Nulls' AND YEAR IS NOT NULL)
)