Help Now Interview Questions and Answers

SQL query to find latest record in a table with and without subquery

• Without subquery: SELECT * FROM table_name ORDER BY date_column DESC LIMIT 1

• With subquery: SELECT * FROM table_name WHERE date_column = (SELECT MAX(date_column) FROM table_name)

Encapsulation, data abstraction, and polymorphism are three fundamental concepts in object-oriented programming.

• Encapsulation is the process of hiding the implementation details of an object from the outside world.

• Data abstraction is the process of representing only the essential features of an object and hiding the unnecessary details.

• Polymorphism is the ability of an object to take on many forms or have multiple beha...read more

Stack is a data structure that follows Last In First Out (LIFO) principle. Queue is a data structure that follows First In First Out (FIFO) principle.

• Stack is like a stack of plates where the last plate added is the first one to be removed

• Queue is like a queue of people waiting in line where the first person added is the first one to be served

• Stack operations: push (add element), pop (remove top element), peek (get top...read more

Caching is the process of storing frequently used data in a temporary storage area for faster access.

• Caching improves application performance by reducing the number of requests to the server.

• It can be implemented at different levels such as browser, server, and database.

• Examples of caching include browser caching of web pages, server caching of API responses, and database caching of query results.

Join types used in SQL to combine data from multiple tables.

• Inner join returns only the matching rows from both tables.

• Left join returns all rows from the left table and matching rows from the right table.

• Outer join returns all rows from both tables, with null values for non-matching rows.

• Examples: SELECT * FROM table1 INNER JOIN table2 ON table1.id = table2.id

• SELECT * FROM table1 LEFT JOIN table2 ON table1.id = table2...read more