CMU DB Systems Notes
# Database Management System
A DBMS is software that allows applications to store and analyze information in a database.
A general-purpose DBMS is designed to allow the definition, creation, querying, update, and administration of databases.
# Early DBMSs
Tight coupling between
# Relational Model
A relation is unordered set that contain the relationship attributes that represent entities.
A tuple is a set of attribute values (also known as its domain) in the relation.
- values are (normally) atomic/scalar
- the special
NULLis a member of every domain
# Primary Keys
A relation's primary key uniquely identifies a single tuple.
Non-aggregated values in SELECT output clause must appear in GROUP BY clause.