SELECT MIN(retail)
FROM books
WHERE category = 'COMPUTER'
工作正常,但是当我在选择中包含标题时:
SELECT MIN(retail), title
FROM books
WHERE category = 'COMPUTER'
它没有。为什么?如何让它发挥作用?
Rhys 的回答是正确的,如果这就是您的意思,但您可能想要title
(s) where retail=MIN(retail)
,并且该措辞暗示了如何获得该答案:
SELECT title, retail
FROM books
WHERE category = 'COMPUTER'
AND retail = (SELECT MIN(retail) FROM books WHERE category = 'COMPUTER')
为了减少重复,您可以使用一个WITH
子句(如果您使用的是最新版本的 SQL):
;WITH ComputerBooks AS (
SELECT title, retail
FROM books
WHERE category = 'COMPUTER')
SELECT title, retail
FROM ComputerBooks
WHERE retail = (SELECT MIN(retail) FROM ComputerBooks)
MIN 适用于一组记录,所以你需要告诉它你指的是哪一组记录。
如果您的意思是每个标题,显示最低零售量,那么您需要:
SELECT MIN(retail), title FROM books
WHERE category = 'COMPUTER'
GROUP BY title