Idfy Interview Questions and Answers

SQL query to retrieve the maximum salary from a database

• Use the SELECT statement with the MAX function to retrieve the maximum salary

• Specify the column name for the salary field in the table

• Example: SELECT MAX(salary) FROM employees

Key concepts of OOP include encapsulation, inheritance, polymorphism, and abstraction.

• Encapsulation: Bundling data and methods that operate on the data into a single unit (class). Example: Class with private fields and public methods.

• Inheritance: Creating new classes based on existing classes, inheriting their attributes and behaviors. Example: Subclass extending a superclass.

• Polymorphism: Objects of different classes can be treated as objects of a common superclass. Example:...read more

Access modifiers control the visibility and accessibility of classes, methods, and variables in programming.

• Public - accessible from anywhere

• Private - accessible only within the same class

• Protected - accessible within the same class and its subclasses

• Internal - accessible within the same assembly

• Protected Internal - accessible within the same assembly or subclasses

Normalization in SQL is the process of organizing data in a database to reduce redundancy and improve data integrity.

• Normalization is a technique used to eliminate redundant data and ensure data integrity.

• It involves breaking down a table into smaller tables and defining relationships between them.

• There are different normal forms such as 1NF, 2NF, 3NF, and BCNF.

• For example, in a database of students and courses, instead of storing student details in the course table, a separa...read more

Procedures do not return a value, while functions return a value.

• Procedures are used to perform an action, while functions are used to calculate and return a value.

• Functions have a return type specified, while procedures do not.

• Example: Procedure to display a message on the screen vs Function to calculate the sum of two numbers.