如何选择所有孩子在SQL中确定条件的父行？

Question

我有两个表是“一对多”的关系。

TblProjects 
ProjectID 
......... 

TblCustomers 
ProjectID 
Number 
......... 

我怎样才能得到所有ProjectIDs为此所有Customers满足这个条件

Number % 100 = 0 

Answer 1

的一般解决方法是使用NOT EXISTS与反向状态（的<>代替=）：

SELECT DISTINCT p.ProjectID 
FROM TblProjects p INNER JOIN TblCustomers ct 
    ON ct.ProjectID = p.ProjectID 
WHERE NOT EXISTS 
    (SELECT 1 
    FROM TblCustomers c 
    WHERE c.ProjectID = p.ProjectID AND (Number % 100) <> 0) 

这是SQLFiddle。

---

或者，具体用于该用途的情况下，可以使用更清洁的查询：

SELECT p.ProjectID 
FROM TblProjects p INNER JOIN TblCustomers ct 
    ON ct.ProjectID = p.ProjectID 
GROUP BY p.ProjectID 
HAVING MAX(ct.Number % 100) = 0 

这里有一个SQLFiddle。

---

P.S.如果你只有需要ProjectID，你根本不需要加入任何东西，只需直接使用TblCustomers即可。

Answer 2

你可以使用内部连接

Select * from tblProjects pro 
inner join tblCustomers cst on pro.projectID = cst.ProjectID 
and cst.Number % 100 = 0 

它会给你你要的

Answer 3

可以使用CTE获得可读查询：

;with 

not_all_at_100 as 
(select distinct c.ProjectID 
    FROM TblCustomers c 
    WHERE (c.Number % 100) != 0 
), 

all_project_customers as 
(select ProjectID 
    FROM TblCustomers 
) 

select distinct p.ProjectID 
from TblProjects p 
where p.ProjectID in (select ProjectID from all_project_customers) 
    and p.ProjectID not in (select ProjectID from not_all_at_100)