如何从2个链接表中查找重复项？

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

我需要根据first_name，last_name和email_address找到重复的联系人。

Answer 1

试试这个

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;