postgreSQL案例:
SELECT
CASE
WHEN (store_size <= (100)::NUMERIC)
THEN '小店'::TEXT
WHEN (store_size >= (200)::NUMERIC)
THEN '大店'::TEXT
ELSE '中店'::TEXT
END AS store_area_level
FROM SALE
注意:
then後的返回值類型要一致。否則會報錯。