簡單的MySql SELECT

Question

我有一個表爲工作日分配工作日ID。

Table: workdays  Table: jobs 
+------+-------+  +------+-----------+ 
| id | days |  | id | jobs  | 
+------+-------+  +------+-----------+ 
| 1 | mon |  | 1 | cleaning | 
| 1 | tue |  | 2 | cooking | 
| 2 | sat |  | 3 | driving | 
| 3 | mon |  | 4 | cleaning | 
| 3 | tue |  | 5 | cooking | 
| 3 | sat |  +------+-----------+ 
| 4 | wed | 
| 4 | mon | 
| 5 | tue | 
+------+-------+ 

這是我用它來選擇的人誰在任何的日工作的ID我指定（比如週一和週二）查詢：

SELECT * FROM workdays WHERE days IN ('mon', 'tue') 

現在，我想選擇那些在我指定的所有日子裏工作的人。我怎樣才能做到這一點？

編輯：增加第二個表。

Answer 1

假設days對於每個id都是唯一的。

SELECT id 
FROM workdays 
WHERE days IN ('mon', 'tue') 
GROUP BY id 
HAVING COUNT(*) = 2 

否則，你需要有DISTINCT在HAVING條款來算唯一的值。

HAVING COUNT(DISTINCT days) = 2