ITPEC FE Morning April 2021 Question 25

Tables linked through column values — the relational model keeps all data in tables and relates them by matching values, not by physical pointers.

In a relational database each relation is a table of rows and columns. One table refers to another by storing a value of the other table's key in one of its columns, a foreign key, and a query joins the tables on those values. No link or pointer between records is stored.

Answer (a)

Why not others:

• •(b) — pairs of an attribute value and the storage location of the records with that value describe an index (an inverted file), not a data model
• •(c) — records joined by links that can form both trees and networks describe the network data model
• •(d) — records joined by pointers limited to a tree, each child with one parent, describe the hierarchical data model

Key rule: Relational means relationships held in data values; the older hierarchical and network models hold them in pointers or links between records.

Databases · AI-written, may contain errors