Mysql：当id具有多个相同值并计算百分比时选择计数

Question

+------+---------+
| id   | object  |
+------+---------+
| 1    |    1    |
| 1    |    2    |
| 1    |    3    |
| 1    |    4    |
+------+---------+

我想选择具有相同值的count id，因此结果是，id 1有4个相同的值，使用SELECT COUNT（*）作为id1 FROM tablename GROUP BY id

+------+
| id1  | 
+------+
| 4    |   
+------+

我有另一张桌子：

+------+---------+
| id2  | object  |
+------+---------+
| 1    |    1    |
| 1    |    2    |
| 1    |    3    |
| 1    |    4    |
| 1    |    5    |
| 1    |    6    |
| 2    |    1    |
| 2    |    2    |
| 2    |    3    |
| 2    |    4    |
| 2    |    5    |
+------+---------+

如何选择结果计数，我仍然不知道如何计算百分比，

+------+---------+
| id1  | id2     |
+------+---------+
|  4   |    6    | # 66%
|  4   |    5    | # 80%
+------+---------+

感谢您的帮助，掌握。

Answer 1

SELECT COUNT(table1.object) as id1,
       COUNT(table2.object) as id2,
       COUNT(table1.object) * 100 / COUNT(table2.object) as percentage
FROM table2
left join table1 on table2.id = table1.id
GROUP BY table2.id