SQL vazifalar to'plami 7.8 Darajasi
Quyidagi jadvallar berilgan:
| id | name | grade |
|---|---|---|
| 1 | John | 91 |
| 2 | Alex | 92 |
| 3 | Evans | null |
| 4 | Alisa | null |
| 5 | Donella | 66 |
| 6 | Lauren | 79 |
| 7 | Matthew | null |
| 8 | Andrew | 62 |
| 9 | Richard | 55 |
| 10 | Sam | null |
| id | subject_id | student_id | grade |
|---|---|---|---|
| 1 | 1 | 5 | 70 |
| 3 | 1 | 6 | 91 |
| 5 | 1 | 9 | 79 |
| 6 | 1 | 8 | 71 |
| 8 | 1 | 2 | 77 |
| 9 | 1 | 1 | 94 |
| id | name |
|---|---|
| 1 | Math |
Ularni quyidagi vazifalarni yeching:
Barcha talabalarning ro'yxatini va ularning o'rtacha bahosini chiqaring, agar talabaning bahosi bo'lmasa, uning o'rtacha bahosi 'NULL' ga teng hisoblanadi.
Barcha talabalarning ro'yxatini va ularning bahosi yo'q fanlar sonini chiqaring.
