我有一个如下表格,我想从两列(fruit1和fruit2)计算不同的值
+------+--------+--------+--------+------+
| 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 |
+------+--------+--------+--------+------+
我可以使用下面的命令对一列进行此操作,但是对于两列没有成功,没有得到如何实现这一点。
选择fruit1,count(*)作为来自s_info group by count1的计数;
导致
+--------+-------+
| 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 |
+--------+-------+
答案 0 :(得分:4)
在进行最终聚合之前使用Manufacturer.find(params[:manufacturer_id])
:
union all