BCS 260 Lecture Notes - Lecture 2: Superkey, Social Media
Document Summary
A key is an attribute or a group of attributes used to identify tuples in the database. Superkeys: an attribute or a group of attributes used to uniquely identify a tuple in the database. Let"s look at every attribute and see if it would make a good superkey. It does uniquely identify every tuple currently in the database. But we can conceive of adding more than one student with the same name. It does uniquely identify every tuple currently in the database and we cannot conceive of adding more than one student with the same social. It doesn"t even uniquely identify everyone thus far. It does uniquely identify everyone thus far, but we know (with our domain knowledge) that it will not continue to. A superkey is an attribute or a group of attributes used to uniquely identify a tuple in the database.
