Probeer het veranderen van de wil van...
count(select * from bookings where b.id_customer = c.id)
...naar...
(select count(*) from bookings where b.id_customer = c.id)
Probeer het veranderen van de wil van...
count(select * from bookings where b.id_customer = c.id)
...naar...
(select count(*) from bookings where b.id_customer = c.id)