SQL Server或MySQL：

select sum(MyColumn) as MyColumnSum from MyTable

如果您需要通过对另一列进行分组来对一列进行求和

select sum(MyColumn) as MyColumnSum, OtherColumn from MyTable Group By OtherColumn

这是一种分别将负数或正数相加的方法

select
  sum( case when MyColumn < 0 then MyColumn else 0 end ) as NegativeSum,
  sum( case when MyColumn > 0 then MyColumn else 0 end ) as PositiveSum
from
  MyTable

参考

• SUM（）的MySQL参考