查询获取显示数量的次数

Question

我需要帮助！

我有这个文件表（这里是简化版）：

       +----+-----+----+
Columns| v1 | v2  | v3 |
       +----+-----+----+
       | 1  | 5   | 11 |
       | 2  | 7   | 5  |
       | 10 | 11  | 18 |
       | 5  | 7   | 10 |
       +----+-----+----+

我想知道显示数字1,2,5,7,10,11和18的次数，与输入的列无关

Answer 1

您可以使用union all“取消”数据，然后使用聚合：

select v, count(*)
from ((select v1 as v from t) union all
      (select v2 as v from t) union all
      (select v3 as v from t) union all
     ) t
group by v;