Question

如何从一张桌子上的多个表中获取数据，我尝试如下，但收到错误。

select login.UserNname,LastLoggedInDetails.LoggedInIP,UserType.UserType,LastLoggedInDetails.LoggedInTime,
LastLoggedInDetails.LoggedOutTime,LastLoggedInDetails.LoggedInVersion,CompanyRegistered.Comp_Name,

case 

when LastLoggedInDetails.LoggedOutTime is not null then CONVERT(VARCHAR(100),DATEDIFF (hour,LastLoggedInDetails.LoggedInTime ,LastLoggedInDetails.LoggedOutTime ))+' Hours '+ 
CONVERT(VARCHAR(100),DATEDIFF (minute,LastLoggedInDetails.LoggedInTime ,LastLoggedInDetails.LoggedOutTime )%60) +' Minutes' as Duration

when LastLoggedInDetails.LoggedOutTime is null then 'Running...' as Duration
end

from LastLoggedInDetails
join login on LastLoggedInDetails.LastLoggedUserId = login.RegistrationId
join UserType on LastLoggedInDetails.LastLoggedUserTypeId = UserType.UserTypeId
join CompanyRegistered on LastLoggedInDetails.RegCompanyId = CompanyRegistered.Comp_Id

Answer 1

以下是case的代码，格式化为有用：

case when LastLoggedInDetails.LoggedOutTime is not null
     then CONVERT(VARCHAR(100),
                  DATEDIFF(hour, LastLoggedInDetails.LoggedInTime, LastLoggedInDetails.LoggedOutTime)
                 ) + ' Hours ' + 
          CONVERT(VARCHAR(100),
                  DATEDIFF(minute, LastLoggedInDetails.LoggedInTime,   
                           LastLoggedInDetails.LoggedOutTime
                          )%60
                  ) +' Minutes' as Duration
--------------------------------^
     when LastLoggedInDetails.LoggedOutTime is null
     then 'Running...' as Duration
end

格式化代码会使问题变得明显：case是一个可以命名的表达式。每个then的单个结果都没有命名。所以，试试这个：

(case when LastLoggedInDetails.LoggedOutTime is not null
      then CONVERT(VARCHAR(100),
                   DATEDIFF(hour, LastLoggedInDetails.LoggedInTime, LastLoggedInDetails.LoggedOutTime)
                  ) + ' Hours ' + 
           CONVERT(VARCHAR(100),
                   DATEDIFF(minute, LastLoggedInDetails.LoggedInTime,   
                            LastLoggedInDetails.LoggedOutTime
                           )%60
                   ) +' Minutes' 
      when LastLoggedInDetails.LoggedOutTime is null
      then 'Running...' 
 end) as Duration

Answer 2

select login.UserNname,LastLoggedInDetails.LoggedInIP,UserType.UserType,LastLoggedInDetails.LoggedInTime,
LastLoggedInDetails.LoggedOutTime,LastLoggedInDetails.LoggedInVersion,CompanyRegistered.Comp_Name,

case 

when LastLoggedInDetails.LoggedOutTime is not null then CONVERT(VARCHAR(100),DATEDIFF (hour,LastLoggedInDetails.LoggedInTime ,LastLoggedInDetails.LoggedOutTime ))+' Hours '+ 
CONVERT(VARCHAR(100),DATEDIFF (minute,LastLoggedInDetails.LoggedInTime ,LastLoggedInDetails.LoggedOutTime )%60) +' Minutes'
when LastLoggedInDetails.LoggedOutTime is null then 'Running...'
end as Duration

from LastLoggedInDetails
join login on LastLoggedInDetails.LastLoggedUserId = login.RegistrationId
join UserType on LastLoggedInDetails.LastLoggedUserTypeId = UserType.UserTypeId
join CompanyRegistered on LastLoggedInDetails.RegCompanyId = CompanyRegistered.Comp_Id

如何使用case语句连接多表？

2 个答案: