在WHERE子句中使用字符串值作为布尔值

Question

是否有可能在where子句中使用值作为类型字符串。像这样：

select * from 
(
select datepart(dw,b.Date) as Tag,b.[Customer No_],b.Date,b.[POS Holiday],b.Nonworking, 
case 
    when datepart(dw,b.Date)=1 then (select '[Valid at Monday]=1') 
    when datepart(dw,b.Date)=2 then (select '[Valid at Tuesday]=1') 
    when datepart(dw,b.Date)=3 then (select '[Valid at Wednesday]=1') 
    when datepart(dw,b.Date)=4 then (select '[Valid at Thursday]=1') 
    when datepart(dw,b.Date)=5 then (select '[Valid at Friday]=1') 
    when datepart(dw,b.Date)=6 then (select '[Valid at Saturday]=1') 
    when datepart(dw,b.Date)=7 then (select '[Valid at Sunday]=1') 
end as TestB 
from [CustomerBPCal] b 
) as a 
left join [CustomerShopAndArrivalTime] as c on c.[Customer No_]=a.[Customer No_] where a.TestB 

如果是，我该如何更改我的代码来运行这样的查询？

Answer 1

标准属于WHERE条款。看来你只是想这样做：

WHERE (datepart(dw, b.Date) = 1 And [Valid at Monday] = 1) 
    OR (datepart(dw, b.Date) = 2 And [Valid at Tuesday] = 1) 
    OR ... 

，或者万一[Valid at ...]列属于outher当然ON子句中加入表CustomerShopAndArrivalTime，则：

ON c.[Customer No_] = a.[Customer No_] 
AND 
( (datepart(dw, b.Date) = 1 And c.[Valid at Monday] = 1) 
OR (datepart(dw, b.Date) = 2 And c.[Valid at Tuesday] = 1) 
OR ... 
)