Question

当PropertyID在Property中出现多次时，我试图从Owner中获取OwnerID，FName，LName。这是我尝试过但我对sql很新的所以我不知道这是否接近。

Select OwnerID, FName, LName 
From Owner 
Where OwnerID = (Select OwnerID 
                 From Property 
                 GROUP BY OwnerID 
                 HAVING Count(*) >=2)

Answer 1

你的意思是：

Select OwnerID, FName, LName 
From Owner 
Where OwnerID In (Select OwnerID 
                 From Property 
                 Group By OwnerID 
                 Having Count(OwnerId) >= 2)

但是如果你想让所有拥有超过1个财产的所有者，那就假设一个财产总是只有一个所有者，而现实世界并不总是如此。

Answer 2

你可以像@Mitch Wheat一样使用IN运算符，或使用EXISTS：

Select OwnerID, FName, LName 
From Owner a
Where EXISTS (Select b.OwnerID 
                 From Property b
                 WHERE a.OwnerID = b.OwnerID
                 Group By b.OwnerID 
                 Having Count(b.OwnerId) >= 2)

Answer 3

按性能我会做

Select OwnerID, FName, LName 
From Owner a
Where EXISTS (Select *
             From Property b
             WHERE a.OwnerID = b.OwnerID
             Group By b.OwnerID 
             Having Count(*) >= 2)

如果在一个表中显示多个SQL查询，则显示其他表数据

3 个答案: