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The SQL Notes for Professionals book is compiled using Stack Overflow Documentation Data Dump. It is an unofficial free book by GoalKicker created for educational purposes. In short, the content is a collection of various people at Stack Overflow. Structured Query Language (SQL) is a programming language designed to manage relational databases. You can create, modify, and optimize database tables according to your needs. The core database modifying operations are performed using INSERT, SELECT, MERGE, UPDATE and DELETE.

SQL is the most used language across all fields of Information technology. Even web developers say that 80% of the time they are storing data and fetching information. Our world revolves around data-driven products, and managing that data has become quite a lucrative career. Even if you are applying for machine learning engineer, the technical interviews will contain a couple of SQL-related questions. To excel in your career and pass the technical interview round of the recruitment process, it is necessary to revise all the concepts. The free SQL book helps you revise all the topics on database management using SQL script and even introduces you to new concepts that can optimize your current process. 

Key Features

The book covers all of the concepts used by SQL query languages, such as data types, order by, group by, Like, case operators, in clause, conditions operations, join and update. Just like me, you will be amazed by unknown terms that are useful for maintaining databases and running efficient SQL queries.  

In this section, we will talk about why this book is special and how you can use these features to improve your knowledge of SQL.

First, every SQL concept comes with practical examples, and you can run the query to practice or just observe the output. The SQL query is an IIF function that creates a new column with categories Bonus and No Bonus.

Every section comes with a question and answer. These are complemented with a detailed explanation of output and how Query has performed. 

SELECT BusinessEntityID, SalesYTD,
IIF(SalesYTD > 200000, 'Bonus', 'No Bonus') AS 'Bonus?'
FROM Sales.SalesPerson
GO

Second, the book starts with simple concepts, like data types and SELECT keywords. With every section, the complexity increases. 

Third, the book covers all the concepts in depth. For example, in the SELECT section, subtopics include SELECT using columns alias, selecting with case and conditions, and selecting with aggregation function. The book covers all SELECT from all angles and then moves to other sections. 

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Fourth, it is a book of SQL cheat sheets. Just like a cheat sheet, the book has a clear description of every function with code. This type of learning helps professionals prepare for presentations or job interviews.

Fifth, the book comprises a high-quality diagram that explains complex concepts. 

Sixth, the long SQL script comes with comments explaining the subquery. The comment helps the developer understand why the nested query was used. 

Last, the book is free and full of quality content. You can find a one-page cheat sheet or search the web for particular terms, but you won't find all of the SQL functions in one place, compiled as a book. 

Conclusion 

At the end of the book, you can see the name of all the people who have contributed to the book. The book is from the community and to the community for free. In this book review, we have learned why it is different from other books and discussed the key features. If you ask me, I will surely use this book to prepare for my next job interview or even use some of the functions to improve my existing projects. Companies are willing to spend money on database optimization and reducing query time. Improve your chance of getting hired and get better at managing data workflow. 

I highly recommend this book to professionals and people who are looking for jobs in the data field. 

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Abid Ali Awan (@1abidaliawan) is a certified data scientist professional who loves building machine learning models. Currently, he is focusing on content creation and writing technical blogs on machine learning and data science technologies. Abid holds a Master's degree in Technology Management and a bachelor's degree in Telecommunication Engineering. His vision is to build an AI product using a graph neural network for students struggling with mental illness.