MySQL Functions

Learn about the most important MySQL functions. On this page, you will find an overview of all key functions, their syntax, and practical examples of use. Functions are divided into different categories based on their application.

LIMIT Clause

The query displays the first names and last names of the first 5 employees from the table. The LIMIT 5 clause limits the results to only 5 records.

SELECT first_name, last_name FROM employees LIMIT 5;

WHERE Clause

The query lists the first name, last name, and salary of all employees working in the "Production" department. The WHERE clause filters the results to display only the employees from this specific department.

SELECT first_name, last_name, salary FROM employees WHERE department = 'Production';

COUNT() Function

The query counts the total number of all employees in the table. The COUNT(*) function returns the number of all rows in the table.

SELECT COUNT(*) FROM employees;

Using DISTINCT

The query counts the number of distinct departments in the company. Using COUNT(DISTINCT department) ensures that each department is counted only once, regardless of how many employees work in an individual department.

SELECT COUNT(DISTINCT department) FROM employees;

ORDER BY Clause

The query lists the first names, last names, and salaries of all employees, sorted by salary from highest to lowest. The ORDER BY salary DESC clause sorts the results so that the highest-paid employees are displayed first.

SELECT first_name, last_name, salary 
FROM employees 
ORDER BY salary DESC;

Average

The query displays data analysis by department. For each department, it calculates the number of employees (using COUNT) and their average salary (using AVG). The results are grouped by department using the GROUP BY clause.

SELECT department, COUNT(*) as employee_count, AVG(salary) as average_salary
FROM employees
GROUP BY department;

MySQL Functions Quick Cheat Sheet

Functions in MySQL allow you to perform mathematical calculations, manipulate text strings, manage dates, and execute advanced conditional data logic directly inside your query. The table below provides a comprehensive overview of the most useful functions with examples for your simulator.