CMST 4100 Chapter : Assignment1
Document Summary
Primary key: a key which is uniquely identifies set of records (columns) in its relational database. It has some set of constraints to it when it is primary key. In each table we should have only one primary key. Candidate key: a candidate key is a single column or whole set of column but should be unique to each other in database. Every candidate key can be qualified as primary key. Super key: a super key is combination of set of columns which are taken collectively. Each column value is defined uniquely: an entity set is a set of entities of same type. Each entity is represented with each attribute (column). A week entity set is entity set that cannot be uniquely defines with its attributes, it must use a foreign key to identify its entities, in other way an entity set without primary key.
