Essential SQL Interview Questions for MySQL Beginners

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The Table — Databases and SQL

2 min readNov 28, 2024

SQL knowledge is fundamental for many tech roles, especially for those working with databases. As a junior developer or aspiring DBA, understanding MySQL is often essential to stand out in interviews. This guide introduces some foundational SQL interview questions, specifically focused on MySQL, that can help you prepare confidently for an upcoming interview. By reviewing core concepts, commands, and SQL best practices, you’ll be ready to demonstrate your MySQL expertise and familiarity with database management.

Essential MySQL Interview Questions

What is a DDL statement in SQL?

Data Definition Language (DDL) statements CREATE, ALTER, and REMOVE database structures.

What is DML in SQL?

Data Manipulation Language (DML) manages data within tables with SELECT, INSERT, UPDATE and DELETE.

What is an index in MySQL, and why is it important?

Indexes enable quick data retrieval by reducing search time. The B-tree index is the most commonly used index type in MySQL.

What are some MySQL storage engines?

MySQL supports multiple storage engines, including

InnoDB — The default engine, supporting transactions and foreign keys.

MEMORY — Stores data in memory, ideal for temporary data.

CSV — Reads and writes CSV files directly.

How can you check the version of MySQL you’re using?

You can find the MySQL version using:

SELECT version();

How can columns be added to an existing table?

To add columns, use this code:

ALTER TABLE your_table 
ADD COLUMN column_name DATATYPE;

How do you rename a table in MySQL?

The syntax to rename a table is.

RENAME TABLE old_table TO new_table;

What is a primary key, and how is it implemented?

A primary key uniquely identifies each record in a table. It is commonly set to auto-increment for efficiency.

id INT AUTO_INCREMENT PRIMARY KEY;

How do you delete all rows in a table?

Use TRUNCATE table_name; to remove all data at once without affecting the table structure.

How can I add a new user to a MySQL database?

To add a user, use the following command:

CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';

How do you join tables in MySQL?

Use the JOIN clause to combine data from two tables based on a related column.

SELECT columns 
FROM table1 
INNER JOIN table2 ON table1.col = table2.col;

What is the default port for MySQL?

MySQL typically runs on port 3306.

Conclusion

Reviewing these MySQL concepts will equip you with the foundational SQL knowledge needed for interviews in junior database and development roles. With this essential preparation, you’ll be able to demonstrate confidence and familiarity with MySQL concepts, from data management commands to user management. Check out the complete guide to SQL interview questions in the article SQL Interview Questions (MySQL): Part 1 to prepare even further.