轉換左外連接到WHERE語句

Question

我希望簡化這一令人困惑的左外通過可能使用其中語句

Select approved.orderId 
From (select distinct orderId from OrderLine where isApproved = 1 and isDismissed = 0) approved 
     left outer join 
     (select distinct orderId from OrderLine where isApproved = 0 and isDismissed = 0) unapproved 
     on approved.orderId = unapproved.orderId 
Where unapproved.orderId Is Null 

喜歡的東西連接語句到的東西更容易閱讀：

Select orderId 
From (select distinct orderId from OrderLine where (isApproved = 1 and isDismissed = 0) OR (isApproved = 0 and isDismissed = 0 and orderId is null)) 

Answer 1

這應該做的：

SELECT DISTINCT O.orderId 
FROM OrderLine O 
WHERE O.isDismissed = 0 
AND O.isApproved = 1 
AND NOT EXISTS(SELECT 1 FROM OrderLine 
       WHERE isApproved = 0 
       AND isDismissed = 0 
       AND orderId = O.OrderId) 

Answer 2

它看起來像連接試圖獲得至少有e批准的生產線但沒有未經批准的生產線。這應該等同於

select distinct orderId 
from OrderLine 
where isApproved = 1 
    and isDismissed = 0 
    AND orderID NOT IN 
     (select orderId 
     from OrderLine 
     where isApproved = 0 
     and isDismissed = 0) 

Answer 3

except應該蠻快的工作，你的用例，並刪除需要兩個連接查詢和內部查詢：

SELECT DISTINCT orderId 
FROM orderline 
WHERE isApproved = 1 and isDismissed = 0 
EXCEPT 
SELECT orderId 
FROM orderline 
WHERE isApproved = 0 and isDismissed = 0