A relational database is based on the relational model and uses a collection of
tables to represent both data and the relationships among those data. It also includes
a DML and DDL.
Each table has multiple columns and each column has a unique name. Figure 1.2
presents a sample relational database comprising two tables: one shows details
of university instructors and the other shows details of the various university
The first table, the instructor table, shows, for example, that an instructor
named Einstein with ID 22222 is a member of the Physics department and has an
annual salary of $95,000. The second table, department, shows, for example, that
the Biology department is located in the Watson building and has a budget of
$90,000. Of course, a real-world university would have many more departments
and instructors. We use small tables in the text to illustrate concepts. A larger
example for the same schema is available online.
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