Company

idname
1yourcompany1
2yourcompany2

Employee

idcompany_idemployee_name
(→ Company.id)
11Employee of yourcompany1
21Another employee of yourcompany1
32Employee of yourcompany2

Position

idposition_titletrades_jobscompany_id
(→ Company.id)
1Position1Construction worker1
2Position2Electrician1
3Position3Construction worker2
4Position4Electrician2

Skill

idskill_typeposition_id
(→ Position.id)
1Skill1Position1
2Skill2Position2
3Skill3Position3
4Skill4Position4