MS访问SQL帮助

Question

我有这个表：

beneficiary  service marks term 
1    eng  50  1 
1    eng     2 
1    math  30  1 
1    math  20  2 
1    com     1 
1    com  70  2 
2    com     1 
2    com  30  2 
2    eng  20  1 
2    eng  30  2 

我怎么能只提取的行，受益人/服务双有标记两个方面在服务 ？

所以从这个表应该只返回：

beneficiary  service mark  term 
1    math  30  1 
1    math  20  2 
2    eng  20  1 
2    eng  30  2 

Answer 1

这时候我将数据导入我的本地数据库，并运行它的工作原理：

SELECT s.* 
FROM scores AS s 
JOIN (
    SELECT beneficiary,service 
    FROM scores 
    WHERE marks IS NOT NULL 
    GROUP BY beneficiary,service HAVING COUNT(*) = 2 
) AS x ON (x.beneficiary = s.beneficiary AND x.service = s.service); 

输出：

beneficiary | service | marks | term 
-------------+---------+-------+------ 
      1 | math | 30 | 1 
      1 | math | 20 | 2 
      2 | eng  | 20 | 1 
      2 | eng  | 30 | 2 
(4 rows)