database – How to join a query with wordpress

I need to join 2 reservation tables in worpress,

    $ wpdb-> get_results ("SELECT * FROM $ db", ARRAY_A);

for example

TO SELECT
b. *
GROUP_CONCAT (ba.NamePack SEPARATOR "
") Extras, (SUM (ba.Price) + b.Price) AS Total OF wp_booking b JOIN LEFT wp_booking_additionals ba ON b.Id_Booking = ba.Fk_IdBooking GROUP BY Id_Booking