Book Image

MySQL 8 Cookbook

By : Karthik Appigatla
Book Image

MySQL 8 Cookbook

By: Karthik Appigatla

Overview of this book

MySQL is one of the most popular and widely used relational databases in the World today. The recently released MySQL 8 version promises to be better and more efficient than ever before. This book contains everything you need to know to be the go-to person in your organization when it comes to MySQL. Starting with a quick installation and configuration of your MySQL instance, the book quickly jumps into the querying aspects of MySQL. It shows you the newest improvements in MySQL 8 and gives you hands-on experience in managing high-transaction and real-time datasets. If you've already worked with MySQL before and are looking to migrate your application to MySQL 8, this book will also show you how to do that. The book also contains recipes on efficient MySQL administration, with tips on effective user management, data recovery, security, database monitoring, performance tuning, troubleshooting, and more. With quick solutions to common and not-so-common problems you might encounter while working with MySQL 8, the book contains practical tips and tricks to give you the edge over others in designing, developing, and administering your database effectively.
Table of Contents (20 chapters)
Title Page
Dedication
Packt Upsell
Contributors
Preface
Index

Functions


Just like stored procedures, you can create stored functions. The main difference is functions should have a return value and they can be called in SELECT. Usually, stored functions are created to simplify complex calculations.

How to do it...

Here is an example of how to write a function and how to call it. Suppose a banker wants to give a credit card based on income level, instead of exposing the actual salary, you can expose this function to find out the income level:

shell> vi function.sql;
DROP FUNCTION IF EXISTS get_sal_level;
DELIMITER $$
CREATE FUNCTION get_sal_level(emp int) RETURNS VARCHAR(10)
 DETERMINISTIC
BEGIN
 DECLARE sal_level varchar(10);
 DECLARE avg_sal FLOAT;

 SELECT AVG(salary) INTO avg_sal FROM salaries WHERE emp_no=emp;

 IF avg_sal < 50000 THEN
 SET sal_level = 'BRONZE';
 ELSEIF (avg_sal >= 50000 AND avg_sal < 70000) THEN
 SET sal_level = 'SILVER';
 ELSEIF (avg_sal >= 70000 AND avg_sal < 90000) THEN
 SET sal_level = 'GOLD';
 ELSEIF (avg_sal...