Question

Given the basic ER and relational models, which of the following is INCORRECT?
1. An attribute of an entity can have more than one value
2. An attribute of an entity can be composite
3. In a row of a relational table, an attribute can have more than one value
4. In a row of a relational table, an attribute can have exactly one value or a NULL value

Answer 1

Correct Answer - Option 3 : In a row of a relational table, an attribute can have more than one value

The correct answer is "option 3".

EXPLANATION:

Option 1: CORRECT

In the Entity-Relationship model or ER model, the Multi-valued attributes of any entity can have one or more attribute values.

In a single-valued attribute, any entity can only have a single attribute value.

Option 2: CORRECT

In ER model, the attribute which can be further broken down into more attribute values is known as the “composite attribute”.

So, an attribute of an entity can be composite.

Option 3: INCORRECT

In the Entity-Relationship model or ER model, the Multi-valued attributes of any entity can have one or more attribute values.

An attribute can have multiple attribute values but not in a row of relational tables.

In a relational table, rows must contain atomic values.

Option 4: CORRECT

In the Relational model, the values of the intersection of one row & column should contain either:

1. Exactly one value or

2. Null value.

Hence the correct answer is “option 3”.