Question

有两列包含相同类型的数据：

col_a  col_b ...
Bob    Tim   ..
John   Frank .
Bob    John
John   Tim
Bob    Bob
Frank  John

现在我要做的查询是这样的（计算事件：（Bob，3），（John，2），..）：

SELECT col_a, count(*) AS total FROM table1 GROUP BY col_a

但是我没有在col_a上运行它，而是想同时在col_a和col_b上运行它（（Bob，4），（John，4），..）

感谢任何帮助

编辑：谢谢你们每个人都很棒。

再次感谢

Answer 1

Select Z.name, Count(*) As Total
From    (
        Select col_a As name
        From total
        Union All
        Select col_b
        From total
        ) As Z
Group By Z.name

Answer 2

select Name, count(*) as Total
from (
    select col_a as Name from MyTable
    union all
    select col_b from MyTable
) a
group by Name

Answer 3

根据您的Bob Bob列，我认为您需要对子查询进行分组：

select idx, sum(count)
from (
    select col_a as idx, count(*) as count
    from table
    union all
    select col_b as idx, count(*) as count
    where col_a <> col_b -- avoid dups
    ) as counts
group by idx

或：

select idx, count(*)
from (
    select col_a as idx
    from table
    union all
    select col_b as idx
    where col_a <> col_b -- avoid dups
    ) as counts
group by idx

对2列进行查询，就像它们是一个一样

3 个答案: