8/1 每日一題(MYSQL 找出重複一次以上的信箱)

Table: Person

+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| id          | int     |
| email       | varchar |
+-------------+---------+
id is the primary key column for this table.
Each row of this table contains an email. The emails will not contain uppercase letters.

 

Write an SQL query to report all the duplicate emails. Note that it's guaranteed that the email field is not NULL.

Return the result table in any order.

The query result format is in the following example.

 

Example 1:

Input: 
Person table:
+----+---------+
| id | email   |
+----+---------+
| 1  | a@b.com |
| 2  | c@d.com |
| 3  | a@b.com |
+----+---------+
Output: 
+---------+
| Email   |
+---------+
| a@b.com |
+---------+ 

Explanation: a@b.com is repeated two times. 

# Write your MySQL query statement below

SELECT email AS Email FROM Person GROUP BY email HAVING COUNT(*)>1;

#從Person表的查詢結果欄位email改別名為 Email

#並將欄位email使用分群並篩選重複一次以上的資料