mysql查询按组和总计数计数

Question

我有一个表'table1'如下：

col1
----
1      
1
2
2
2
3
3

我希望按照以下方式按组和总计数计算：

col1    group_count   total_count
-------------------------------------
1       2             7
2       3             7
3       2             7

我尝试如下：

SELECT col1, group_count, total_count FROM 
(SELECT col1, COUNT(col1) AS group_count FROM table1 GROUP BY col1) Temp1, 
(SELECT COUNT(col1) AS total_count FROM table1) Temp2

如何以优化方式完成

Answer 1

优化的方法是首先计算计数，然后简单地将变量放在select语句中：

set @rowCount = (select count(col1) from table1);
select col1, count(col1), @rowCount from table1 group by col1;

See the result

@Meherzad给出的方法将多次计算行数。但是如果你想在一个查询中执行此操作，你可以使用：

select col1, count(col1), (select count(col1) from table1) rowCount from table1 group by col1;

Answer 2

尝试此查询

select col1, count(*), tot 
from tbl t1, (select count(*) as tot from tbl) t2 
group by col1

Fiddle