How to count rows in one table based on another table in mysql

Question

I have two tables in a MySQL database. The first one has a list of department names.

departments
    abbreviation | name
    -------------|-------------
             


        

Answer 1

Try this

SELECT d.abbreviation, COUNT(*) num
FROM departments d
INNER JOIN courses c ON c.section LIKE CONCAT(d.abbreviation, "%")
GROUP BY d.abbreviation