Multi-level constraints
I'm tracking workers in the construction industry. The industry is classified into trades - Laborer, Operating Engineer, Carpenter, etc. Each worker can have one or more trades. Within each trade there are specializations or skills. For example, an Operating Engineer could have the skills to use one or more specific machines (digger, bobcat, crane, etc). I need to track each worker's trades and each worker's specialization, if any. Which trade(s) a worker has will determine the pool of specializations/skills he/she can have. How can I create restrictions so that the worker can only have the skills that fall under his/her trade? Below is a simplified sample of my schema: Worker Name John Barbara Trade Name Laborer Operating Engineer WorkerTradeJunction Worker Trade John Laborer Barbara Operating Engineer Skill Skill Trade Pile Driver Laborer Digger Operating Engineer WorkerSkillJunction Worker Skill John Pile Driver Barbara Digger Again: How can I make it so that Barbara (Operating Eng) cannot have the skill of Pile Driver and John (Laborer) cannot have the skill of Digger? Thank you!
