SQL meseleleri 6.2 derejesi

Tablisalar berlen:

customers
id name email registration_date
1 Evans evan@gmail.com 2010-10-10
2 John john@gmail.com 2008-05-01
3 Alec alec@gmail.com 2016-12-30
orders
id customer_id order_date total_amount
1 1 2023-10-10 3200
2 1 2023-05-10 1600
3 1 2023-01-13 500
4 3 2023-05-31 1200
5 3 2023-05-28 2500
6 3 2023-06-06 5000

Olara şu meseleleri çözüň:

Задание 1

Her bir müşderi tarapyndan edilen sargytlaryň sanyny hasaplaň.

Задание 2

Sargady bolmadyk müşderileri tapyň.