I need to count and show how many bike-rentals every customer have. Included customers that haven't rented a bike. But how?

Question

SELECT Customer.MobileNr, COUNT(*) AS NumberOfRentals

FROM Customer, Rental

WHERE Customer.MobileNr = Rental.MobileNr

GROUP BY Customer.MobileNr

(This doesn't include customers that haven't rented a bike)

Answer 1

// Select all of them and later count them individual by php, or select 2 times

Answer 2

W. Khalid I have 0 mysql workbench you cand this then:

select * from NumberOfRentals where Customer.MobileNr in ('rented', 'notrendet')

Answer 3

Use a Left outer join:

SELECT Customer.MobileNr, COUNT(Rental.MobileNr) AS NumberOfRentals

FROM Customer left join Rental
On Customer.MobileNr = Rental.MobileNr

GROUP BY Customer.MobileNr

Answer 4

Sudarshan Rai 👑 I'm doing it on MySql workbench, will it work?

Answer 5

PapaBT will this include Customers that doesn't exist in Rental? (haven't rented yet)