左外部聯接到生成的表？

Question

我的做法完全錯誤嗎？ 我想對從2個表生成的查詢進行左外部聯接，但我不斷出錯。 我需要其他方法嗎？

1：

ID, Surname,Firstname

2：

ID,JobNo,Confirmed

我有以下查詢：

SELECT JobNo AS N, StaffID AS P, Confirmed as C, 
       FirstName AS F,Surname AS S 
FROM gigs_players, Players 
WHERE t1.StaffID=t2.StaffID AND JobNo="2" 
      AND (`Confirmed` IS NULL OR Confirmed ='Y' ) 
ORDER BY Instrument,Surname

我要添加：

LEFT OUTER JOIN contacted (ON t1.StaffID=contact.ID AND t2.JobNo=contact.JobNo)"

我可以對從2個表生成的查詢進行left outer join聯接嗎？

Answer 1

為了在要添加的左外部t2中使用t1和t2 ，需要將它們與第一個表聯接，您不能在左外部聯接中直接引用它們，如下所示：

SELECT JobNo AS N, StaffID AS P, Confirmed as C, 
   FirstName AS F,Surname AS S 
FROM gigs_players, Players
Inner join t1 on ...
Inner join t2 on ...
LEFT OUTER JOIN contacted c 
     on t1.StaffID=c.ID AND t2.JobNo = c.JobNo
WHERE t1.StaffID=t2.StaffID AND JobNo="2" 
    AND (`Confirmed` IS NULL OR Confirmed ='Y' ) 
ORDER BY Instrument,Surname

因此，根據表的結構，用t1和t2其他表的兩個聯接的條件。

Answer 2

這是左連接子查詢的示例。 這可能是您要尋找的。

select 
parts.id, 
min(inv2.id) as nextFIFOitemid 
from test.parts 
left join 
( select 
  inventory.id, 
  coalesce(parts.id, 1) as partid 
  from test.inventory 
  left join test.parts 
  on (parts.id = inventory.partid) 
) inv2 
on (parts.id = inv2.partid) 
group by parts.id;