How to prevent double booking

[Kenny_Luck]

I am facing a problem with double booking , i don't know where to start to write the code that a customer can't rental the same car at for the same day. For example, if a customer choose to book car A from 1/8/2018 till 10/8/2018 , how do i avoid that other customer won't book on the date 1/8/2018 or even 2/8/2018 and so on. Pls help me is quiet urgent

[Barand]

Easiest way...

+--------------+                                +-------------+
|   Car        |                                | customer    |
+--------------+                                +-------------+
| car_id  (PK) |--+                          +--| cust_id (PK)|
| reg_no       |  |                          |  | name        |
| make         |  |                          |  +-------------+
| model        |  |                          |
+--------------+  |                          |
                  |                          |
                  |   +-------------------+  |
                  |   |  booking          |  |
                  |   +-------------------+  |
                  |   |  booking_id  (PK) |  |
                  +--<|  car_id      (UQ) |  |
                      |  hire_date   (UQ) |  |
                      |  cust_id          |>-+
                      +-------------------+

In the booking table (car_id, hire_date) is defined as a unique key and a record is written for each day that the car is hired. Because the key is unique, booking it to another customer on one of those dates will throw an error and the transaction should be cancelled.

Edited September 16, 2019 by Barand

[Kenny_Luck]

so if i wan to like rent the car starting with 11/8/2018 is still possible right ??

 

[Barand]

Yes, so long as there is no record for another customer containing 

car A  |   2018-08-11

(There is a tutorial on resource booking in my signature)

Edited September 16, 2019 by Barand

[Kenny_Luck]

i see thanks , if i got any problem i will ask it , thanks for your help