This document provides an overview of SQL and database concepts. It defines what a database is and common database terminology like tables, rows, records, and fields. It describes the different types of database users and common database architectures like single-tier, two-tier, and three-tier. Entity-relationship modeling and database schemas are also explained, along with keys, relationships, and mapping cardinalities. The document concludes with a discussion of Codd's 12 rules for relational databases.