如何從2個鏈接表中找到重複項？

Question

Table 1 : Contacts 
Fields : id | first_name | last_name 

Table 2 : email (it contains contact_id of contacts table) 
Fields : id | contact_id | email_address 

我需要根據first_name,last_name和email_address找到重複的聯繫人。

Answer 1

試試這個

SELECT R.first_name , R.last_name, S.email_address 
FROM Table1 R 
INNER JOIN Table2 S ON R.id = S.Contactid 
Group By R.first_name , R.last_name, S.email_address 
Having Count(S.Contactid)>1;