在sql server中連接表？

Question

在SQL Server中，我加入瞭如下所示的三個表。

select t1.empid, t2.sales, t3.date 
from table1 t1 
left outer join table2 t2 on t1.empid = t2.empid 
left outer join table3 t3 on t1.empid = t2.empid 
    and t2.id= t3.id 

這是正確的，我用and的條件，謝謝。

，如果我寫的PROC：我正在使用joing左外部表連接

select wrh.empid 
from Tbl_F_Weekly_Report_Header WRH 
left outer join Tbl_Emp_Master_M EM on wrh.EmpId =em.EmpId 
LEFT outer join Tbl_F_Emp_Position_M EPS on WRH.PositionCode = EPS.PositionCode 
where EM [Tbl_Emp_Master_M] doesnot contain Positioncode 

是正確

Answer 1

你LEFT OUTER JOIN上表3是不正確。你只需要：

SELECT t1.empid, t2.sales, t3.date 
FROM table1 AS t1 
LEFT OUTER JOIN table2 AS t2 ON t1.empid = t2.empid 
LEFT OUTER JOIN table3 AS t3 ON t2.id = t3.id 

，因爲你已經在第一LEFT OUTER JOIN

你更新的查詢指定上述t1.empid = t2.empid：

SELECT wrh.empid 
FROM Tbl_F_Weekly_Report_Header AS wrh 
LEFT OUTER JOIN Tbl_Emp_Master_M AS em ON wrh.EmpId = em.EmpId  
LEFT OUTER JOIN Tbl_F_Emp_Position_M AS eps ON wrh.PositionCode = eps.PositionCode 

看起來不錯，只要確定你包括FROM（最初失蹤從你的問題）

Answer 2

你剛剛錯過選擇>選擇和t3左外連接。您必須使用SQL Server Management Studio來測試您的查詢。

select 
t1.empid, 
t2.sales, 
t3.date 
from table1 t1 
left outer join table2 t2 on t1.empid=t2.empid 
left outer join table3 t3 on t2.id= t3.id 

問候

Answer 3

是你的SQL語句是正確的。但你可以試試這個：

select t1.empid, t2.sales, t3.date 
from table1 t1 
left outer join table2 t2 on t1.empid = t2.empid 
inner join table3 t3 on t2.empid = t3.empid 

或

select t1.empid, t2.sales, t3.date 
from table1 t1 
left outer join table2 t2 on t1.empid = t2.empid 
left outer join table3 t3 on t2.empid = t3.empid