sql 中取整，四舍五入取整，向下取整，向上取整。

SELECT
 round(52.45, 0) AS round4,
 round(52.54, 0) AS round5,
 round(52.45, 1) AS round41,
 round(52.54, 1) AS round51,
 floor(52.4) AS floor4,
 floor(52.5) AS floor5,
 ceiling(52.4) AS ceiling4,
 ceiling(52.5) AS ceiling5

round是四舍五入

floor是向下取整

ceiling 是向上取整

round需要一個位數的參數

floor和ceiling都取到整數，不含小數。