GROUP BY operatori NULL qiymatlarni qanday ishlaydi?

GROUP BY operatori NULL qiymatlarni alohida guruh sifatida ishlov beradi. Guruhlash ustunida NULL bo'lgan barcha satrlar bu yagona NULL guruhiga kiradi.

Misol:

Faraz qilaylik, bizda category (String) va price (double) ustunlariga ega products jadvali bor:

category	price
Electronics	100
Electronics	200
NULL	50
Clothing	30
NULL	70

So'rovni bajarish:

SELECT category, AVG(price)
FROM products
GROUP BY category;

Natija taxminan quyidagicha bo'ladi:

category	AVG(price)
Electronics	150.0
NULL	60.0
Clothing	30.0