Sql 基于整型字段计算新列

我有一个包含整数列的表，名为“Day1Reg”、“Day2Reg”、“Day7Reg”、“Day1OT”、“Day2OT”、“Day7OT”。我想选择表中的所有行，计算两个名为“WkReg”和“WkOT”的新列，它们将是DayxReg和DayxOT的总和。Dayx列可能为空。以下是到目前为止的问题：

select
  *,
  (Day1Reg+Day2Reg+Day3Reg+Day4Reg+Day5Reg+Day6Reg+Day7Reg) as WkReg,
  (Day1OT+Day2OT+Day3OT+Day4OT+Day5OT+Day6OT+Day7OT) as WkOT
from
  Week01
where
  UserName = "JustMe"

---

WkReg和WkOT列已创建，但没有值。在几个Dayx列中都有整数值。没有返回错误，只返回WkReg和WkOT中的空白值。

推测，一些整数值是

NULL

，这导致整个总和为

NULL

。您可以使用

coalesce（）

将值替换为

0

：

UPDATE `Week01` SET `WkReg` = (Day1Reg+Day2Reg+Day3Reg+Day4Reg+Day5Reg+Day6Reg+Day7Reg), 
`WkOT`=(Day1OT+Day2OT+Day3OT+Day4OT+Day5OT+Day6OT+Day7OT) 
WHERE `UserName` = "JustMe"

select w.*
       (coalesce(Day1Reg, 0) + coalesce(Day2Reg, 0) + coalesce(Day3Reg, 0) +
        coalesce(Day4Reg, 0) + coalesce(Day5Reg, 0) + coalesce(Day6Reg, 0) + coalesce(Day7Reg, 0)
       ) as WkReg,
       (coalesce(Day1OT, 0) + coalesce(Day2OT, 0) + coalesce(Day3OT, 0) +
        coalesce(Day4OT, 0) + coalesce(Day5OT, 0) + coalesce(Day6OT, 0) + coalesce(Day7OT, 0)
       ) as WkOT
from Week01 w
where w.UserName = 'JustMe';