Find Users With Valid E-Mails || Leetcode sql solution || Easy solution || Fully-Explained || 💯💯💯✅✅✅🔥🔥🔥

 

1517. Find Users With Valid E-Mails

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.

Fully-Explained Solution :

To write SQL query for selecting all rows from the Users table where the mail column to match with a regular expression pattern that describes a valid email address with has the domain @leetcode.com.

REGEXP :- It is the sequence of characters that specifies a match pattern in text

Approach :-

The regular expression pattern  should contain'^[a-zA-Z][a-zA-Z0-9._-]*@leetcode\\.com'

1. ^ : specifies the starting charater of string
2. [a-zA-Z]: matches only one upper or lower case letter in this sequence.
3. [a-zA-Z0-9._-]*: matches zero or more letter of upper or lower case letter, digit, underscore, period, or dash.
4. @leetcode\\.com: matches the string @leetcode.com, where the backslash is used to escape the period character.

Finally, This SQL query returns all rows from the Users table

1. the mail column starts with a letter ^[a-zA-Z],
2. followed by zero or more occurrences of letters, digits, underscores, periods, or dashes, [a-zA-Z0-9._-]*
3. ends with @leetcode.com , '@leetcode\.com'

This satisfies the condition of a valid email address

SQL Query :-

SELECT *
FROM Users
WHERE mail REGEXP '^[a-zA-Z][a-zA-Z0-9._-]*@leetcode\\.com' ;