INTRO.TO INFO.SYSTEMS (LOOSELEAF)
INTRO.TO INFO.SYSTEMS (LOOSELEAF)
7th Edition
ISBN: 9781119362883
Author: Rainer
Publisher: WILEY
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Chapter 5, Problem 12DQ
Program Plan Intro

Table:

A table is a group of related information held in an organized format within a database. The table consists of rows and columns.

Primary key:

  • In relational databases, a primary key is a key that is used for identifying and defining the characteristics uniquely of each row.
  • A primary key may have a single attribute or a multiple attributes.

Example:

Let us consider the “Student” table that consists of “Student_ID”, “First_Name”, “Last_Name”, and “Course_ID” as attributes.

  • Student_ID act as the primary key.

Foreign key:

  • A primary key attribute in one table is the foreign key for another table. In a logical way, a foreign key is used to establish a relationship between two tables.
  • A foreign key is used for identifying a row of another table uniquely.
  • Foreign keys are represented in italic form.

Example:

The following example describes about the foreign key.

Consider the “Student” table which consists of “Student_ID”, “First_Name”, “Last_Name”, and “Course_ID” are attributes and the “Course” table contains the attributes such as “Course_ID” and “Course_Name”.

  • In this, “Student_ID” act as the primary key and the “Course_ID” act as a foreign key, because it is used to refer the “Course” table.

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