2025

What is a composite key?

August 16, 2025

A composite key in a database is a primary key that consists of two or more columns in a table....

What is the difference between UNION and UNION ALL?

August 16, 2025

The difference between UNION and UNION ALL in SQL is subtle but important. Let’s break it down clearly: 1. UNION...

Joins in mysql

August 16, 2025

In MySQL, joins are used to combine rows from two or more tables based on a related column between them....

What is the difference between WHERE and HAVING?

August 16, 2025

The difference between WHERE and HAVING in SQL is subtle but important. Let’s break it down clearly: Aspect WHERE HAVING...

What is denormalization?

August 16, 2025

Denormalization is the process of intentionally introducing redundancy into a database that has been normalized. In simpler terms, it’s the...

What is normalization? Explain different normal forms.

August 16, 2025

Normalization is a database design technique used to organize data in a relational database efficiently. The main goals of normalization...

Explain the difference between CHAR and VARCHAR.

August 16, 2025

In MySQL, CHAR and VARCHAR are both used to store text/string data, but they behave differently in terms of storage,...

What are constraints in MySQL?

August 16, 2025

In MySQL, a constraint is a rule applied to a column or table that limits the type of data that...

What is a Primary key vs Foreign key

August 16, 2025

Let’s break it down clearly: Primary Key (PK): student_id name age 1 Alice 20 2 Bob 21 Here, student_id is...

What is the difference between MyISAM and InnoDB?

August 16, 2025

Here’s a detailed comparison between MyISAM and InnoDB, the two main MySQL storage engines: Feature MyISAM InnoDB Transaction Support ❌...