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:
Hemme talyplaryň sanawyny we olaryň ortaça bahasyny çykaryň, şonda eger talybyň bahasy ýok bolsa, onuň ortaça bahasy 'NULL' deň hasaplanýar.
Hemme talyplaryň sanawyny we olaryň bahasy ýok bolan predmetleriň sanyny çykaryň.
