题目 
ActorDirector表:
| Colun Nae | Type | 
|---|---|
| actor_id | int | 
| director_id | int | 
tiestap | int | 
tiestap 是这张表的主键.
写一条SQL查询语句获取合作过至少三次的演员和导演的 id 对(actor_id, director_id)
示例:
ActorDirector 表:
| actor_id | director_id | tiestap | 
|---|---|---|
| 1 | 1 | 0 | 
| 1 | 1 | 1 | 
| 1 | 1 | 2 | 
| 1 | 2 | 3 | 
| 1 | 2 | 4 | 
| 2 | 1 | 5 | 
| 2 | 1 | 6 | 
Result 表:
| actor_id | director_id | 
|---|---|
| 1 | 1 | 
唯一的 id 对是 (1, 1),他们恰好合作了 3 次。
题解 
sql
SELECT `actor_id`, `director_id`
FROM `ActorDirector`
GROUP BY `actor_id`, `director_id`
HAVING COUNT(1) >= 31
2
3
4
2
3
4