Question

我需要列出存在活跃员工的数据库中的所有城市。如果城市存在于多个州，我想将州名添加到其中。所以我尝试做类似的事情：

SELECT Locations.LocationID,
    CASE
        WHEN Locations.City IS NOT DISTINCT
            THEN Locations.City + '(' + ISNULL(Locations.State,'') + ')'
        ELSE Locations.City
    END as LocationDescription
FROM Locations
    INNER JOIN Employees on Locations.LocationID = Employees.LocationID
WHERE Employees.Active=1 
ORDER BY LocationDescription

显然，这不是正确的语法，我使用的是DISTINCT，但不知道如何解决这个问题。

Answer 1

我会选择每次添加状态，但是，如果您真的想这样做，可以使用GROUP BY和IN条款......

WHEN Locations.City IN (SELECT Locations.City FROM Location GROUP BY City HAVING COUNT(*) > 1)

Answer 2

你可以使用相关的子查询来完成它，但是不总是更容易附加状态吗？它也会使输出更加一致......

可能有更聪明的方法，但这应该有用。

SELECT l.LocationID,
    CASE
        WHEN (SELECT COUNT(City) FROM Locations WHERE L.city = city) > 1
            THEN l.City + '(' + ISNULL(l.State,'') + ')'
          ELSE l.City
    END as LocationDescription
FROM Locations L
    INNER JOIN Employees on l.LocationID = Employees.LocationID
WHERE Employees.Active=1 
ORDER BY LocationDescription

DISTINCT时选择CASE

2 个答案: