Database Fundamentals

What is a Database?
General:
• A database is any collection of related data.
Restrictive:
• A database is a persistent, logically coherent collection of inherently meaningful data, relevant to some aspects of the real world.

What is a Database Management System?
A database management system (DBMS) is a collection of programs that enables users to create and maintain a database.

What Does a DBMS Do?
Database management systems provide several functions in addition to simple file management:
• allow concurrency
• control security
• maintain data integrity
• provide for backup and recovery
• control redundancy
• allow data independence
• provide non-procedural query language
• perform automatic query optimization

Who Interacts with a DBMS?
Many different individuals are involved with a database management system over its life:
• systems analysts
• database designers
• database administrators
• application developers
• users

Relational Database Model:
What is a relational database?
• a database that treats all of its data as a collection of relations

What is a relation?
• a kind of set
• a subset of a Cartesian product
• an unordered set of ordered tuples