Chapter 3 The Relational Model
Review Questions
3.1 Discuss each of the following concepts in the context of the relational data model:
(a) Relation (b) Attribute (c) Domain (d) Tuple (e) Intension and Extension (f) Degree and Cardinality.
Each term defined in Section 3.2.1.
Domain – Set of atomic (indivisible) values.
Attribute – it describes a component of the database, such as a table or a field.
N-tuple – in mathematics, an ordered set of n elements called its components or coordinates.
Relation Schema – It is representation of database highlighting relationships that we have created.
Relation State – set of tuples that have the same attributes. …show more content…
Discuss the difference between a view and a base relation.
View is the dynamic result of one or more relational operations operating on the base relations to produce another relation. Base relation exists as a set of data in the database. A view does not contain any data, rather a view is defined as a query on one or more base relations and a query on the view is translated into a query on the associated base relations.
Exercises
The following tables form part of a database held in a relational DBMS:-
Hotel (hotelNo, hotelName, city) Room (roomNo, hotelNo, type, price) Booking (hotelNo, guestNo, dateFrom, dateTo, roomNo) Guest (guestNo, guestName, guestAddress)
where Hotel contains hotel details and hotelNo is the primary key; Room contains room details for each hotel and (roomNo, hotelNo) forms the primary key; Booking contains details of the bookings and (hotelNo, guestNo, dateFrom) forms the primary key; and Guest contains guest details and guestNo is the primary key.
3.8 Identify the foreign keys in this schema. Explain how the entity and referential integrity rules apply to these
Review Questions
3.1 Discuss each of the following concepts in the context of the relational data model:
(a) Relation (b) Attribute (c) Domain (d) Tuple (e) Intension and Extension (f) Degree and Cardinality.
Each term defined in Section 3.2.1.
Domain – Set of atomic (indivisible) values.
Attribute – it describes a component of the database, such as a table or a field.
N-tuple – in mathematics, an ordered set of n elements called its components or coordinates.
Relation Schema – It is representation of database highlighting relationships that we have created.
Relation State – set of tuples that have the same attributes. …show more content…
Discuss the difference between a view and a base relation.
View is the dynamic result of one or more relational operations operating on the base relations to produce another relation. Base relation exists as a set of data in the database. A view does not contain any data, rather a view is defined as a query on one or more base relations and a query on the view is translated into a query on the associated base relations.
Exercises
The following tables form part of a database held in a relational DBMS:-
Hotel (hotelNo, hotelName, city) Room (roomNo, hotelNo, type, price) Booking (hotelNo, guestNo, dateFrom, dateTo, roomNo) Guest (guestNo, guestName, guestAddress)
where Hotel contains hotel details and hotelNo is the primary key; Room contains room details for each hotel and (roomNo, hotelNo) forms the primary key; Booking contains details of the bookings and (hotelNo, guestNo, dateFrom) forms the primary key; and Guest contains guest details and guestNo is the primary key.
3.8 Identify the foreign keys in this schema. Explain how the entity and referential integrity rules apply to these