如果查询出MySQL里某字段值最小的记录ID号？

Question

哪位老大给指点一下啊，我在MySQL里建立一个表room,里面有三个字段：roomID, roomName, guestNumber.
我想查询出guestNumber最小的那个记录的roomID
该怎么写呢？ 我写的是 select * from room where guestNumber=min(guestNumber),运行提示：invalid use of group function

Answer 1

使用聚合函数min()求最小值，对应max()求最大值。
SELECT roomID FROM room WHERE guestNumber = (SELECT MIN(guestNumber) FROM room)

Answer 2

select * from room where guestNumber=(select min(guestNumber) from room)

Answer 3

select min(guestNumber) from room