Question

我有两组表，帐户上的所有联系人都有他们的标题等。出于数据迁移的目的，我需要从表A中选择具有表B中不存在的AccountID的所有ContactsIds。它是ContactId和AccountID的组合。我尝试过以下方法：

Select * from Final_Combined_Result wfcr 

 WHERE NOT EXISTS (Select Contact_ID, Account_ID from Temp_WFCR)

我知道这完全没了，但是我在这里看了几个其他问题但是找不到合适的解决方案。

我也试过这个：

Select * from Final_Combined_Result wfcr  
WHERE NOT EXISTS 
  (Select Contact_ID, Account_ID from Temp_WFCR as tc 
   where tc.Account_ID=wfcr.Account_InternalID 
   AND tc.Account_ID=wfcr.Contact_InternalID)

这似乎是正确的，但我想确定一下。

Answer 1

Select wfcr.ContactsId, wfcr.AccountID
from Final_Combined_Result wfcr 
left join Temp_WFCR t_wfcr ON t_wfcr.ContactsIds = wfcr.ContactsId 
                          AND t_wfcr.AccountID = wfcr.AccountID
WHERE t_wfcr.AccountID is null

请参阅this great explanation of joins

Answer 2

@ juergend的答案显示了左连接。

使用a not exists加入subselect，它看起来像这样：

Select wfcr.*
from 
  Final_Combined_Result wfcr 
  WHERE NOT EXISTS 
     (Select 1 --select values dont matter here, only the join restricts.
     from 
       Temp_WFCR t
     where t.Contact_ID = wfcr.Contact_InternalID
       and t.account_id = wfcr.Account_InternalID 
     )

选择表A中不在表B中的列组合

2 个答案: