Page 453 - Computer_Science_F5

Computer Science Access, MySQL, and PostgreSQL.
(a) Names of tables

The names of the tables are route, bus_company, and schedule
(b) Names of columns
(i) The table route has the following columns: route_number, route_ name,
FOR ONLINE READING ONLY
origin, destination.
(ii) The table bus_company has the following columns: company_ id, route_
number, owner_name, post_code.
(iii) The table schedule has the following columns: schedule_number, route_
number, departure_time, arrival_time.
(c) Data types
(i) The data type for route_number, company_id, schedule_number, and
post_code will be integer.
(ii) The data type for route_name, origin, destination, and owner_name will
be characters of varying length (preferably 50 characters).
(iii) The data type for departure_time and arrival_time will be date time or
time (depending on your preference).

Note: The physical data model and relationships between entities will be covered
in more detail in this chapter’s subsequent sections.

key, candidate key, alternate key, foreign
Activity 8.2:
key, selection, and projection.
Designing a Data Model
(a) Attribute or field
Following the real-life example
provided, design a data model for a Attributes or fields describe characteristics
shop encompassing conceptual, logical, or properties that define all items about
and physical data models. Focus on a particular category. An attribute is also
three key entities. a named column in a database. e.g., first
name, postal code, and date of birth in the
employees’ database.
Relational database terminologies
and their application (b) Tuple or record
As mentioned earlier, the relational A tuple or record is a data set representing
database is a type of database that focuses a single item. It is a collection of related
on the relationship between stored data data fields or attributes. It is also known
elements. The fundamental terminologies as a row in a database. An example of a
applied to relational databases include record is, for instance, when you have
attribute, tuple, relation, domain, primary an employee’s database with attributes
first_name, post_code, and date_of_

444
for Advanced Secondary Schools

Computer Science Form 5.indd 444 23/07/2024 12:34