MySQL 查询具有按同一列分组的多个计数条件

Question

我不熟悉使用 group by 进行 MySQL 查询

我有这些表:

• user 包含以下列:userid、position、dept_id、status
• 部门，包含以下列:dept_id、name

我想要一个查询来计算位置为 ojt、subcon 的所有用户， 所有部门的状态均为辞职

所以我有一个看起来像这样的表格:

SEDC dept:
ojt users count: 13
subcon users count: 32
resigned users count: 2


HR dept:
ojt users count: 2
subcon users count: 3
resigned users count: 1

Finance dept:
ojt users count: 4
subcon users count: 6
resigned users count: 1

Answer 1

尝试这个查询

select a.nam,case when position='ojt' then acount else o end as ojtuser
case when position='subcon' then acount else o end as subconuser
regincount 
  from department a
join(
select dept_id,Position,Count(*) acount from user
group by Dept_id,Position)b on a.dept_id=b.dept_id
join(
select dept_id,Count(*) regincount from user status=resigned
group by dept_id)c on a.dept_id=c.dept_id