A database schema is a set of relation schemas. Changes to a schema or database schema are expensive. So, careful thought must be given to design of a database schema. A database schema defines a database in terms of tables, keys, indexes and constraints.

Example of a database schema:
employee(emp_name, birth_date, social_security_no, dept_name),
department(dept_name, function).

Various objects of a schema :
• Fields
• Records
• Tables
• Database