Can a relation have multi valued attributes?
The Relational Data Model
In relational design theory, a row in a relation has the following properties: Only one value at the intersection of a column and row: A relation does not allow multivalued attributes.
What is difference between attribute and property?
Attribute is a quality or object that we attribute to someone or something. For example, the scepter is an attribute of power and statehood. Property is a quality that exists without any attribution. For example, clay has adhesive qualities; i.e, a property of clay is its adhesive quality.
How do you handle multi-valued attributes?
The only way to handle multiple values of the same attribute is to create an entity in which you can store multiple instances, one for each value of the attribute (for example, Figure 5-9). In the case of the employee entity, we would need a dependent entity that could be related to the employee entity.
What is the difference between single valued attribute and multi-valued attribute?
Answer: The attributes that can have only one value for a given entity are called the single-valued attributes. For example, the attribute Book_title is a single-valued attribute as one book can have only one title. The attributes that can have multiple values for a given entity are called multi-valued attributes.
Can a multivalued attribute be a primary key?
Multivalued attributes cannot work as primary keys. Actually, multivalued attributes violate First Normal Form. So the good idea is to create a separate table and push multivalued attribute into it.
Can a multivalued attribute be composite?
Some Composite keys can also be a multivalued attribute. For example, the address attribute of a student can further be divided into ‘Locality’, ‘Town’ and ‘PIN’. So, we call it a composite attribute. Also, the address of a student can have more than one value.
What is multivalued attribute in normalization?
A multi-valued attribute would contain more than one value for that field in each row.
Which of the following can be multivalued attribute?
Which of the following can be a multivalued attribute? Explanation: Name and Date_of_birth cannot hold more than 1 value. Explanation: None.
What is the difference between composite attribute and multivalued attribute?
For example, Location as the attribute of an entity called ENTERPRISE is multivalued, because each enterprise can have one or more locations. Composite Composite attributes are not atomic because they are assembled using some other atomic attributes.
How are multivalued attributes depicted?
Multivalued Attribute: – Attributes that can have many values (there are many distinct values entered for it in the same column of the table). – Multivalued attribute is depicted by a dual oval.
What is the difference between composite attribute and composite key?
A composite attribute includes multiple atomic attributes such as the address field. In the case of the “address” field for an employee table it may include street no, town name, house no, Zip code. On the contrary the Composite key acts as a unique identifier that is used to identify a row from the table uniquely.
Is a date a multivalued attribute?
multi-valued attribute: Consider a PERSON entity. The person it represents has (one) SSN, (one) date of birth, (one, although composite) name, etc.
How do you convert a multivalued attribute to a table?
Rule: To convert a multivalued attribute in an ER diagram into relational schema, we need to create a separate table for multivalued attribute along with the primary key of the base table.
How do we represent multivalued attribute in a table while converting ER diagram to table?
In the given ER diagram, COURSE_ID, STUDENT_ID, SUBJECT_ID, and LECTURE_ID are the key attribute of the entity. The multivalued attribute is represented by a separate table.
How a multivalued attribute can be solved in a relational mapping?
Step 6: Mapping of Multivalued attributes.
– For each multivalued attribute A, create a new relation R. – This relation R will include an attribute corresponding to A, plus the primary key attribute K-as a foreign key in R-of the relation that represents the entity type of relationship type that has A as an attribute.
How are multivalued attributes indicated in the Chen entity relationship model?
In the Chen ERM, multivalued attributes are shown by a double line connecting the attribute to the entity. The Crow’s Foot notation does not identify multivalued attributes.
When all multivalued attributes have been removed from a relation it is said to be in?
Terms in this set (44) When all multivalued attributes have been removed from a relation, it is said to be in: first normal form.