TECHNICAL INTERVIEW QUESTIONS AND ANSWERS 1 TO 5

1.POLYMORPHISM:

         The word “Polymorphism” means having many forms. Polymorphism occurs when there is a hierarchy of classes and related by Inheritance. The most common use of Polymorphism in OOP occurs when a parent class reference is used to refer a child class. Real time example: A person having different charactersitics.

2.LINKED LIST:

         Linked List is a Linear Data Structure. It is not stored in at contiguous memory locations. The elements in the linked list are stored using pointer.

         Simple we can say that list consist of nodes where each node consists of data and reference link to the next node.

3.NORMALISATION:

         Database normalisation is a database schema technique, by which an existing schema are modified to minimize redundancy and dependency of data.

         Normalisation splits large table to smaller tables and define relationship between them to  increase the clarity in organizing the data.

To Know About All The Normal Forms : Click here.

4.JOINS:

         Join Clause is used to combine rows from two or more tables, based on related column between them.

Different Types Of SQL Joins:

1. Inner Join
2. Left Outer Join
3. Right Outer Join
4. Full Outer Join

 

5.SQL Keys:

         Keys help us to uniquely identify a row in a table by a combination of one or more columns in a table.

Student ID	Name	Marks
101	Akshay	488
102	Balaji	476
103	Dinesh	476

        

          In this table “Student ID” is the primary key.

Need of a Key: Keys help you to uniquely identify any row in a table.

Keys in DBMS:

1. Super Key
2. Candidate Key
3. Primary Key
4. Alternate Key
5. Foreign Key
6. Compound Key
7. Composite Key
8. Surrogate Key