[英]How to select rows from MySQL table only if count of rows matching index meets value?
[英]How to select only rows from a table one clumns value is more than b table count value in MySQL
表A:
id, name, school_code
-------------------
1,David,10601
2,Jack,10602
3,John,10603
4,Hank,10602
5,Daisy,10601
6,Kelly,10602
7,May,10602
8,Mayme,10602
表B:
id, school_code,max_stu
------------------------
1,10601,10
2,10602,5
3,10603,6
如何選擇表B行max_stu的值多於表A計數(*)其中a.school_code = b.school_code?
預期結果:
id, school_code,max_stu
------------------------
1,10601,10
3,10603,6
一種方法將使用相關子查詢。 這與你已經制定它的方式非常相似。
SELECT *
FROM `table b` `b`
WHERE `b`.`max_stu` > (SELECT count(*)
FROM `table a` `a`
WHERE `a`.`school_code` = `b`.`school_code`);
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