What are unary, binary, and ternary relations?

Integrity constraints are the rules defined on a relational database schema and satisfied by all the instances of database in order to model the real-world concepts correctly. They ensure the consistency of database while the modifications are made by the users. For example, the integrity constraint ensures that the value of ISBN in BOOK relation cannot be duplicated or null.

A database can be defined as a collection of related data from which users can efficiently retrieve the desired information. A database can be anything from a simple collection of roll numbers, names, addresses and phone numbers of students to a complex collection of sound, images and even video or film clippings. Though databases are generally computerized, instances of non-computerized databases from everyday life can be cited in abundance. A dictionary, a phone book, a collection of recipes and a TV guide are examples of non-computerized databases. The examples of computerized databases include customer files, employee rosters, books catalog, equipment inventories and sales transactions.