Question

I need to display records from my sql from the parent table that have child records less than 4 or no child records, Need SQL query please.

More Clarification:

1. having no child records of a parent at all is also fine, all parent records should display
2. If the parent record has child records between 1 and 3, should display
3. if the parent record has exactly 4 child records, it shouldn’t be displayed.

Schema (an employee can’t have more than 4 donations)

client (client_id, email)

employee (employee_id, name)

donation (donation_id, employee_id, client_id)

SQL I’ve tried.

SELECT * FROM employee left join 
(SELECT donation_id, employee_id, client_id, count(employee_id) as count from donation      GROUP BY employee_id HAVING count <= 4) as d
ON employee.employee_id = d.employee_id

Answer 1

You can just join the tables, group by employee and filter the groups for those with less than 4 records:

SELECT   employee.*
FROM     employee LEFT JOIN donation USING (employee_id)
GROUP BY employee_id
HAVING   COUNT(*) < 4