sql中COUNT()+GROUP BY +HAVING的组合使用

图上为一个子菜单表，每个菜单都有对应的parentid。

1.统计每个parentid下有多个子菜单

SELECT parentid,COUNT(*) AS num FROM xt_menu GROUP BY parentid

 

结果53条，如下

2.统计parentid下有大于10个子菜单的parentid

SELECT parentid,COUNT(*) AS num FROM xt_menu GROUP BY parentid HAVING COUNT(*)>10;

 

结果15条，如下