Interview Questions and Answers

The number of rectangles formed can be calculated using the formula n*(n+1)*(2n+1)/6.

• Use the formula n*(n+1)*(2n+1)/6 to calculate the number of rectangles.

• The number of squares can be used as the value of n in the formula.

• Consider all possible combinations of squares to form rectangles.

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

• Join is used to retrieve data from multiple tables.

• Syntax: SELECT column_name(s) FROM table1 JOIN table2 ON table1.column_name = table2.column_name;

• Types of joins: INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL OUTER JOIN, CROSS JOIN.

• Example: SELECT customers.name, orders.order_date FROM customers JOIN orders ON customers.customer_id = orders.customer_id;

Constrain is a rule that restricts the values in a database column. DDL is a set of SQL commands used to create, modify, and delete database objects.

• Constrains ensure data integrity and prevent invalid data from being inserted into a database.

• DDL includes commands like CREATE, ALTER, and DROP to manage database objects like tables, indexes, and views.

• Constrains are defined using DDL commands like CHECK, UNIQUE, and FOREIGN KEY.

• DDL is used to define the structure of a database...read more

Exceptions are unexpected events that occur during the execution of a program and disrupt the normal flow of the program.

• Exceptions are used to handle errors and other exceptional conditions in a program.

• They can be caught and handled using try-catch blocks.

• Examples of exceptions include NullPointerException, ArrayIndexOutOfBoundsException, and IOException.

A linked list is a data structure in Java that consists of a sequence of nodes, each containing a reference to the next node.

• Linked list is a dynamic data structure that can grow or shrink during runtime

• It can be singly linked or doubly linked

• Insertion and deletion operations are faster compared to arrays

• Traversal of linked list is slower compared to arrays

• Example: LinkedList class in Java