sql - SQL 查询是否在一个表中出现多次显示另一表数据

Question

当 OwnerID 在 Property 中出现多次时，我试图从 Owner 获取 OwnerID、FName、LName。这是我尝试过的，但我对 sql 很陌生，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：

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

但是，如果您试图让所有拥有超过 1 个财产的所有者，则假定财产始终只有一个所有者，而现实世界中并非总是如此。

Answer 2

您可以使用 IN 运算符，如 @Mitch Wheat 答案，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

按表现我会做

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)