mysql更新選擇語句與多個表和左外連接

Question

我有兩個表，hires_owner和項目，其中hires_owner是項目中的數據的彙總表。我想定期用項目數據更新hires_owner。表結構如下：

**hires_owner** 

id INT(11) AUTO-INCREMENT 
owner CHAR(25) UNIQUE 
hires_total INT(3) 

Sample data: 
1, tim, 0 
2, jack, 3 
3, brian, 1 
etc. 

和

**projects** 

id INT(11) AUTO-INCREMENT 
date DATE() **this is the report date stamp, not date of activity 
owner CHAR(25) 
accept DATE() 

sample data: 
1, 2014-02-01, jack, 2014-01-02 
2, 2014-02-01, jack, 2014-01-03 
3, 2014-02-01, tim, NULL 
etc. 

這個查詢得到我，我想推入hires_owner表中的結果：

select owner, count(accept) 
from projects 
where date = (select max(date) from projects) 
group by owner 

...但我可以似乎沒有得到正確的更新查詢。這裏有一個嘗試：

update hires_owner h 
set hires_total = p.Hires 
(select owner, count(accept) as Hires 
from projects 
where date = (select max(date) from projects) 
group by owner) p 
where p.owner = h.owner 

Answer 1

試試這個： -

update 
hires_owner h 
inner join 
(select owner, count(accept) num_c 
from projects 
where date = (select max(date) from projects) 
group by owner) p 
on h.owner = p.owner 
set h.hires_total = num_c 

Answer 2

您的查詢沒有指定要更新哪個所有者，並且它有點扭曲邏輯。 更新，讓我知道結果。

update hires_owner set hires_total = p.m 
from (select max(count(accept)) as m, owner as o 
        from projects 
        where date = (select max(date) from projects) 
        group by owner) as p 
where hires_owner = p.o;