摘要：
题目：Write a SQL query to find all duplicate emails in a table namedPerson.+----+---------+| Id | Email |+----+---------+| 1 | a@b.com || 2 | c@d.co... 阅读全文
摘要：
题目：TheEmployeetable holds all employees including their managers. Every employee has an Id, and there is also a column for the manager Id.+----+------... 阅读全文