数值进取

ROUND(X,D) 四舍五入

表示将值 X 四舍五入为小数点后 D 位的数值，默认 D 的数值为0。若要保留 X 值小数点左边的 D 位，可将 D 设为负值。

SELECT
    ROUND( '3141.5926' ) AS '3142',
    ROUND( '3141.5926', 0 ) AS '3142 as 0',
    ROUND( '3141.5926', 1 ) AS '3141.6 as 1',
    ROUND( '3141.5926', - 2 ) AS '3100 as -2';

FLOOR(X) 向下取整

只返回值X的整数部分，小数部分舍弃。

SELECT
    FLOOR( '3141.5926' ) AS '3141';

CEILING(X) 向上取整

返回值X的整数部分，如果小数部分大于0，则返回结果+1

SELECT
    CEILING( '3141.0001' ) AS '3142';