in_column.md

# 列子查询

Joe 打算写一个查询，根据员工表

```mysql
create table employee(
    id int primary key auto_increment,
    dept varchar(256),
    name varchar(256),
    post varchar(16)
)
```

统计每个部门的人数，但是他不打算用 group by。那么还可以怎做？

## 答案

```mysql
select distinct(dept) as dept, 
               (select count(*) from employee as i where i.dept=o.dept) as emp  
from employee as o
```