20. When one-to-one relationship in E-R model is mapped into relational data mod
ID: 3850593 • Letter: 2
Question
20. When one-to-one relationship in E-R model is mapped into relational data model, the one-to-one relationship is generally represented as
a. a primary key.
b. a foreign key.
c. a primary key in one table and a foreign key in another table or the same table of the primary key.
d. a table with a pair of foreign keys, each of which is associated to a primary key in its parent table.
21. When one-to-many relationship in E-R model is mapped into relational data model, the one-to-one relationship is generally represented as
a. a primary key.
b. a foreign key.
c. a primary key in one table and a foreign key in another table or the same table of the primary key.
d. a table with a pair of foreign keys, each of which is associated to a primary key in its parent table.
22. When many-to-many relationship in E-R model is mapped into relational data model, the one-to-one relationship is generally represented as
a. a primary key.
b. a foreign key.
c. a primary key in one table and a foreign key in another table or the same table of the primary key.
d. a table with a pair of foreign keys, each of which is associated to a primary key in its parent table.
Explanation / Answer
20. c a primary key in one table and a foreign key in another table or the same table of the primary key.
A primary key in a table represent a unique enttry of that table. Now a one-to-one maping means a value of 1 table should means a value in another table.
So primary key in one table will represent a unique entry and a foreign key with value of that primary key will br representing one value of that table.
21 b. a foreign key.
22. d. a table with a pair of foreign keys, each of which is associated to a primary key in its parent table
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.