8. PGT Computer Science Question Discussion

8. PGT Computer Science Question Discussion

Given the basic ER and relational models, which of the following is INCORRECT?

(A) An attribute of an entity can have more than one value

(B) An attribute of an entity can be composite

(C) In a row of a relational table, an attribute can have more than one value

(D) In a row of a relational table, an attribute can have exactly one value or a NULL value

Explanation

Option C is correct.

 

 First Two options are related to ER Model and In E-R diagram we can have multi valued and composite attributes so those two options are correct.

            Last Two options are related to Relational model 

According to Relational Model every relation should be in 1NF and according to 1 NF, there should not be a multi-valued attribute in a relation. That means an attribute can have only one value or NULL value in a row. So statement of option C is incorrect