How do i do a join query in mysql on this scheme - mysql

Question

I'm having some trouble trying to get all the data out of this database in one query.
Here is the Database scheme
I know that there is a way to do this with a join but i'm not sure how.
I need all the data from Questionnaire, Booking, and Customers.
I think i have to join on the Booking has customers but i'm not sure.
At the moment i have something like this
SELECT *
FROM Booking,Questionaires,Customers
WHERE accepted = 0
JOIN ON Booking_idBooking = Customers_idCustomers
Can anyone help me out?
Thanks beforehand!

Answer 1

You could use inner join this way
SELECT * FROM Booking_idBooking as BB
INNER JOIN Booking as B on BB.Booking_idBooking = B.idBooking
INNER JOIN Customers as C on BB.Customers_idCustomers = C.idCustomers
INNER JOIN Questionaires as Q on Q.idQuestionaires = B.uestionaires_idQuestionaires
WHERE B.accepted = 0 ;

Answer 2

I would go about doing something like this, but you may need left joins depending one your circumstances.
select
*
from
customers c
inner join booking_has_customers bhs on
bhs.Customers_idCustomers = c.idCustomers
inner join booking b on
b.idBooking = booking_idBooking
inner join Questionaires q on
q.idQuestionaires = b.Questionairs_idQuestionairs
where
b.accepted = 0;
Just a note, you should really change your naming conventions.
For example booking is singular, yet customers is plural in your schema. They should be consistent. Also, something like idBooking and booking_idBooking is not great - maybe use id and booking_id. Anyway just suggestions.
You also might want to invest some time in learning how to write joins. Checkout w3schools for good examples.

Answer 3

SELECT b.*,q.*,c.*
FROM Booking AS b
JOIN Questionaries AS q ON q.idQuestionaries=b.Questionaries_idQuestionaries
JOIN Booking_has_Customers AS bhc ON bhc.Booking_idBooking=b.idBooking
JOIN Customers AS c ON c.idCustomers=bhs.Customers_idCustomers
WHERE b.accepted=0
But come on, change ID names into simple id and you'll have:
SELECT b.*,q.*,c.*
FROM Booking AS b
JOIN Questionaries AS q ON q.id=b.id
JOIN Booking_has_Customers AS bhc ON bhc.id=b.id
JOIN Customers AS c ON c.id=bhs.id
WHERE b.accepted=0