This booklet describes the basics of relational database concepts, theory, and query languages (SQL). It starts simple, explaining what a relation is, what a relational database is, and various design issues. For this purpose, it uses an easy-to-understand, yet non-trivial, example of a database to keep track of students,courses, and departments in a university. Along the way it also covers the concept of ER design. It then describes, in detail, relational query languages such as relational algebra, tuple calculus, and domain calculus. It then builds on these, and describes SQL in detail. Finally, it covers the topics of data integrity, functional dependencies, and database normalization, with illustrative examples.
