lessons
---------------------------------------------------------
| id | keyskill_id |
---------------------------------------------------------
| 1 | 3 |
---------------------------------------------------------
| 2 | 5 |
---------------------------------------------------------
| 3 | 2 |
---------------------------------------------------------
| 4 | 3 |
---------------------------------------------------------
| 5 | 1 |
---------------------------------------------------------
| 6 | 5 |
---------------------------------------------------------
| 7 | 4 |
---------------------------------------------------------
| 8 | 2 |
---------------------------------------------------------
| 9 | 5 |
---------------------------------------------------------
lesson_requiredskill_relations
---------------------------------------------------------
| lesson_id | requiredskill_id |
---------------------------------------------------------
| 7 | 2 |
---------------------------------------------------------
| 7 | 3 |
---------------------------------------------------------
| 1 | 12 |
---------------------------------------------------------
| 1 | 17 |
---------------------------------------------------------
| 1 | 5 |
---------------------------------------------------------
| 3 | 17 |
---------------------------------------------------------
| 4 | 14 |
---------------------------------------------------------
| 8 | 12 |
---------------------------------------------------------
| 8 | 18 |
---------------------------------------------------------
Но в качестве варианта решения проблемы имеет право на существование.
Спасибо!