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Formatted question description: https://leetcode.ca/all/1517.html
1517. Find Users With Valid E-Mails
Level
Easy
Description
Table: Users
+---------------+---------+
| Column Name | Type |
+---------------+---------+
| user_id | int |
| name | varchar |
| mail | varchar |
+---------------+---------+
user_id is the primary key for this table.
This table contains information of the users signed up in a website. Some e-mails are invalid.
Write an SQL query to find the users who have valid emails.
A valid e-mail has a prefix name and a domain where:
- The prefix name is a string that may contain letters (upper or lower case), digits, underscore
'_', period'.'and/or dash'-'. The prefix name must start with a letter. - The domain is
'@leetcode.com'.
Return the result table in any order.
The query result format is in the following example.
Users
+---------+-----------+-------------------------+
| user_id | name | mail |
+---------+-----------+-------------------------+
| 1 | Winston | winston@leetcode.com |
| 2 | Jonathan | jonathanisgreat |
| 3 | Annabelle | bella-@leetcode.com |
| 4 | Sally | sally.come@leetcode.com |
| 5 | Marwan | quarz#2020@leetcode.com |
| 6 | David | david69@gmail.com |
| 7 | Shapiro | .shapo@leetcode.com |
+---------+-----------+-------------------------+
Result table:
+---------+-----------+-------------------------+
| user_id | name | mail |
+---------+-----------+-------------------------+
| 1 | Winston | winston@leetcode.com |
| 3 | Annabelle | bella-@leetcode.com |
| 4 | Sally | sally.come@leetcode.com |
+---------+-----------+-------------------------+
The mail of user 2 doesn't have a domain.
The mail of user 5 has # sign which is not allowed.
The mail of user 6 doesn't have leetcode domain.
The mail of user 7 starts with a period.
Solution
Use regular expression. The prefix name must start with a letter, and may only contain letters, digits, underscores periods and dashes. The domain must be @leetcode.com.
# Write your MySQL query statement below
select * from Users
where mail regexp '^[a-zA-Z]+[a-zA-Z0-9_\\./\\-]{0,}@leetcode.com$'
order by user_id;