SQL meseleler toplumy 7.8 derejesi
Tablisalar berlen:
| 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 |
Olara üçin aşakdaky meseleleri çözüň:
Задание 1
Hemme talyplaryň sanawyny we olaryň ortaça bahasyny çykaryň, şonda eger talybyň bahasy ýok bolsa, onuň ortaça bahasy 'NULL' deň hasaplanýar.
Задание 2
Hemme talyplaryň sanawyny we olaryň bahasy ýok bolan predmetleriň sanyny çykaryň.