Where Do Keys Come From? 1.Just assert a key K. The only FD's are K->A for all attributes A. 2. Assert FD's and deduce the keys by systematic exploration. 3. More FD's From "Physics" Example:no two courses can meet in the same room at the same time"tells us: hour room -course. 1313 Where Do Keys Come From? 1. Just assert a key K. – The only FD’s are K -> A for all attributes A. 2. Assert FD’s and deduce the keys by systematic exploration. 3. More FD’s From “Physics” - Example: “no two courses can meet in the same room at the same time” tells us: hour room -> course