NIELIT 2016 MAR Scientist C - Section C: 5

Question

A primary key, if combined with a foreign key creates

• A. parent child relationship between the tables that connect them
• B. many-to-many relationship between the tables that connect them
• C. network model between the tables that connect them
• D. none of these

Answer 1

Foreign key is used to create a existential dependency like for example consider Employee and Dependent tables. In this case the primary key of Employee table is employee_id. In the Dependent table we will have an employee_id field which will refer to employee_id field of Employee table (foreign key). An employee dependent can exist only if the employee entry exist in Employee table. This creates a parent child relationship.

A foreign key entry can refer to a single parent key entry but multiple foreign key entries can refer to the same parent key entry. So, this is a $m:1$ (many-to-one) relationship.

So A is correct.

Comments

For such questions, if you are not able to answer it is pretty bad. Giving reference link should be for things one is not able to explain. It looks pretty bad to see all answers being copied here from some site albeit with reference.

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Have edited the answer. Will keep that point in mind. Thanks.

Answer 2

option A is correct.Parent-child relationship between the tables that connect them.

Answer 3

1. parent child relationship between the tables that connect them

the primary table will act as the parent table while the table with the foreign key will act as the child table.In such a case,one parent can have more than one child,creating a one to many relationship

Answer 4

THE CORRECT ANSWER IS OPTION A, IT CREATES PARENT CHILD RELATIONSHIP WHERE DEPENDENT TABLE BECOMES CHILD AND OTHER BECOMES PARENT. ALSO IN ANY TABLE P-KEY IS ALWAYS BUT USING THEM AS F-KEY WE CAN FOR MANY TO 1 RELATIONSHIPS.