在 where 子句中使用 case 语句

Question

您好，由于我的代码错误，我丢失了一些东西。

select * from ##ScheduleDetail SD
left join ##HolidayFilterTbl HF on SD.Scheduledate = HF.Testdate

where (ScheduleDate = testdate)
and
(Case 
 when HF.IsHoliday = 1 then (overtime = 1 and makeup = 0)
 else
(overtime = 0 and Makeup = 0)
end
)
and
DOW = 5 
order by ActivityStartTime

我尝试了几种组合，但每种组合都在第一个等号或第二个等号处出错。我缺少什么？

Answer 1

表达式的分支case只能返回值，而不能返回where条件中要计算的其他表达式。但是，您可以使用and和or逻辑运算符来模拟此行为：

select    *
from      ##ScheduleDetail SD
left join ##HolidayFilterTbl HF on SD.Scheduledate = HF.Testdate
where     (ScheduleDate = testdate) and
          ((HF.IsHoliday = 1 and overtime = 1 and makeup = 0) or
           (overtime = 0 and Makeup = 0)) and
          DOW = 5 
order by  ActivityStartTime

请注意，问题中表达式makeup = 0的两个分支（或答案中表达式的两侧）都有，因此您可以将其从中提取出来并稍微简化条件：caseor

select    *
from      ##ScheduleDetail SD
left join ##HolidayFilterTbl HF on SD.Scheduledate = HF.Testdate
where     ScheduleDate = testdate and
          makeup = 0 and
          ((HF.IsHoliday = 1 and overtime = 1) or
           overtime = 0) and
          DOW = 5 
order by  ActivityStartTime