mysql求和

1.求某列指定字段之和（一列多行）：sum（字段名）

select t.Status,sum(t.Amount)from table t

where t.CreateTime between '2018-05-29 00:00:00' and '2018-05-29 23:59:59'

group by t.Status;

2.求几个字段之和(一行多列)

SELECT t.列1 + t.列2 + t.列3 AS Total FROM table t

WHERE t.time = '2018-05-29 00:00:00';

或

SELECT SUM(t.列1 + t.列2 + t.列3)  AS Total FROM table t

WHERE t.time = '2018-05-29 00:00:00';