Question

我有两张桌子 - 一张用于工作人员，另一张用于子女。

如何根据儿童人数对人进行分组？

员工表

pID|name|family|ETC|  
---- |-------- |-------|-------|    
123 |abc|ddd   | 134 | f |   
124 |dfv |eee   | 900 | d |     
126 |rgt |wwww|750|m|

儿童表

pID|name|family|ETC|        
---- |-------- |-------|-------|    
123 |mah|ddd |2005/06/09|son |    
123 |dar|ddd |2013/11/01|girl|    
123 |sia|ddd |2003/01/01|girl|    
126 |naz|wwww|2007/25/01|girl|

预期表格

pID|no|        
----- |- |    
123 |3|    
124 |0|    
126 |1|

Answer 1

从staff加入children，按pID分组将为您完成工作：

select
    S.pID,
    count(C.name) as no
from staff as S
    left outer join childern as C on C.pID = S.pID
group by S.pID

Answer 2

试试这个

select S.pID,
(select isnull(COUNT(*),0) from children C where C.pID=S.pID)
from Staff S

Answer 3

select s.pId
     , (select count(*) from [children] c where c.pId = s.pId)
  from [staff] s;

将[children]和[staff]替换为您的实际表名。

Answer 4

SELECT staff.pid,count(*) FROM staff,children WHERE staff.pid=children.pid GROUP BY staff.pid;

此查询将为您提供结果输出。

Answer 5

如果你想要所有PiD的结果（即使他们是0个孩子），那么使用：

select
  staff.pID,count(children.name) as count
from staff
  left outer join childern on childern.pID = staff.pID
group by S.pID

（Andy Korneyev的答案相同）

但是，如果您只想让孩子数（大于0），请使用：

select
  staff.pID,count(children.name) as count
from staff
  inner join childern on childern.pID = staff.pID
group by S.pID

希望这有帮助。

计数基于sql server中另一个表的行数

5 个答案: