本文将详细介绍MySQL中如何实现以SQL查询返回的结果集取交集的实现方法，需要的朋友可以参考

1

MySQL中如何实现以下SQL查询

(SELECT S.Name

FROM STUDENT S, TRANSCRIPT T

WHERE S.StudId = T.StudId AND T.CrsCode = 'CS305')

INTERSECT

(SELECT S.Name

FROM STUDENT S, TRANSCRIPT T

WHERE S.StudId = T.StudId AND T.CrsCode = 'CS315')

请各位不吝赐教，小弟先谢过~

解：

取交集

select a.* from

(

SELECT S.Name

FROM STUDENT S, TRANSCRIPT T

WHERE S.StudId = T.StudId AND T.CrsCode = 'CS305'

) as a

cross join

(

SELECT S.Name

FROM STUDENT S, TRANSCRIPT T

WHERE S.StudId = T.StudId AND T.CrsCode = 'CS315'

) as b on a.Name = b.Name;

2.

SELECT * FROM (

SELECT DISTINCT col1 FROM t1 WHERE...

UNION ALL

SELECT DISTINCT col1 FROM t1 WHERE...

) AS tbl

GROUP BY tbl.col1 HAVING COUNT(*) = 2

3.

交集：

SELECT * FROM table1 AS a JOIN table2 AS b ON a.name =b.name

举例：

表a:

FieldA

001

002

003

表b:

FieldA

001

002

003

004

请教如何才能得出以下结果集，即表A, B行交集

FieldA

001

002

003

答案：select a.FieldA from a inner join b on a.FieldA=b.FieldA

差集：

NOT IN 表示差集

SELECT * FROM table1 WHERE name NOT IN (SELECT name FROM table2)