Mysql 对两列进行查询，就好像它们是一列一样

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：Bob，3，John，2，…：

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

但是我不想在a列上运行它，我想同时在a列和b列上运行它，鲍勃，4，约翰，4

谢谢你的帮助

编辑： 谢谢大家，你太棒了

再次感谢

基于您的Bob Bob专栏，我认为您需要分组子查询：

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

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：

---

快速回答！Z作为别名吗？>让我头疼@N8-Z是任意的。可以使用任何您喜欢的别名，只要您使用别名。

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

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