How to count the number of emails per domain in PostgreSQL MySQL Oracle

In this article, we will see how to count the number of emails per domain, we can use the following query in SQL Server or PostgreSQL or MySQL or Oracle or any RDBMS:

To count the number of emails per domain in PostgreSQL MySQL Oracle:

SELECT 
    SUBSTRING(
        email, 
        CHARINDEX('@', email)+1, 
        LEN(email)-CHARINDEX('@', email)
    ) domain_name,
    COUNT(email) emails_count
FROM 
    sales.customers
GROUP BY
    SUBSTRING(
            email, 
            CHARINDEX('@', email)+1, 
            LEN(email)-CHARINDEX('@', email)
        );

Output:

domain_name emails_count

gmail.com     11234
ymail.com     9842
hotmail.com   2944
r2schools.com 4000
aol.com       3201

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