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Relational model General information
32 U929-J-Z125-9-76
The following list shows the terms used in this manual and the corresponding formal terms
defined by Codd:
In the relational model, the data is managed and processed in the form of tables.
Different types of tables exist:
– base tables
– result tables
–views
Base tables
Base tables are tables that have a fixed definition within the database. In figure 3, the
database contains two base tables with the table names DEPARTMENT and EMPLOYEES.
A table is composed of lines and columns. The base table in the relational model is compa-
rable to the record type in the CODASYL model. A line of a table is called a record. A record
of the EMPLOYEES table contains all the information on a given employee. Instead of the
term “column”, this manual uses the term “record element”.
Result tables
Querying the database yields a new table, a result table, which contains the records
returned in response to the query.
Views
A view is a defined section of a database. A view may contain record elements and records
from one or more base tables. Views can be addressed with SQL statements in the same
way as a base table can. The use of views can afford a vast simplification of the database
interface and provide a large degree of logical data independence.
Term used in manual Formal term (Codd)
table
record (row)
column, record element
value
value range
relation
tuple
attribute
attribute value
domain