使用SQL命令时遇到问题

Question

我在SQL Server 2012中遇到了问题。我遇到的问题是，当我在查询中尝试运行case语句时，case语句之前的列变得无法识别。

我已经分离的问题，并发现这是块：

Select 
    [Address 1] + 
    Case 
     when [Address 2] = '' then ',' + [Address 2] 
     else '' end 
    Case 
     when Town <> '' then ',' + rtrim(Town) 
     else '' end 
    Case when County&lt;&gt;'' then ','+rtrim(County) else '' end 
) as Address 
from Employees 

任何帮助将是巨大的，因为我仍然在学习SQL。

以下是完整的代码块：

Select 
    'Chorley' as [Site Address], 
    [EmpID] as EmployeeID, 
    [First Name], 
    [Surname], 
    Manager as [Manager directly over employee], 
    Email, 
    '' as WorkPhone, 
    [Home Tel], 
    [Mobile Tel], 
    (
    [Address 1] + 
    Case when [Address 2] = '' then ',' + [Address 2] else '' end 
    Case when Town <> '' then ',' + rtrim(Town) else '' end 
    Case when County&lt;&gt;'' then ','+rtrim(County) else '' end) as Address, 
    Pcode, 
    [NI No], 
    DOB, 
    [Job Title], 
    [Start Date], 
    [Hours Worked], 
    [Days And Times] as DaysAndTimes, 
    Holidays, 
    '', 
    [Contract] as 'Contract' 
from Employees 
where [Employment Status]<>'Leaver' 
Order By [Department], [SurName] 

Answer 1

必须使用情况之间的+以串联：

之前

Select [Address 1]+ 
     Case when [Address 2] = '' then ',' + [Address 2] else '' end 
     Case when Town <> '' then ',' + rtrim(Town) else '' end 
     Case when County<>'' then ','+rtrim(County) else '' end) as Address 
from Employees 

后

Select [Address 1]+ 
     Case when [Address 2] = '' then ',' + [Address 2] else '' end + 
     Case when Town <> '' then ',' + rtrim(Town) else '' end + 
     Case when County<>'' then ','+rtrim(County) else '' end) as Address 
from Employees