mysql - 如何从两列中获取不同值的计数？

Question

我有一个如下表，我想计算两列(fruit1 和 fruit2)中的不同值

+------+--------+--------+--------+------+
| s_id | s_name | fruit1 | fruit2 | rs   |
+------+--------+--------+--------+------+
|    1 | ram    | apple  | mango  |   20 |
|    2 | raj    | apple  | banana |   13 |
|    3 | aman   | orange | banana |    7 |
|    4 | mangal | orange | apple  |   16 |
|    5 | ravi   | apple  | banana |   17 |
|    6 | pawan  | apple  | apple  |    9 |
|    7 | shyam  | apple  | orange |   11 |
+------+--------+--------+--------+------+

我可以使用以下命令为一列执行此操作，但不能为两列成功，不知道如何实现。

select fruit1, count(*) as count from s_info group by fruit1;

结果是

+--------+-------+
| fruit1 | count |
+--------+-------+
| apple  |     5 |
| orange |     2 |
+--------+-------+

但下面是我的预期结果，我没有得到。

+--------+-------+
| fruits | count |
+--------+-------+
| apple  |     7 |
| orange |     3 |
| banana |     3 |
| mango  |     1 |
+--------+-------+

Answer 1

在进行最终聚合之前使用union all:

select fruit, count(*)
from ((select fruit1 as fruit from s_info) union all
      (select fruit2 as fruit from s_info)
     ) i
group by fruit;