SQL: The powerful language to extract data from databases

Structured Query Language (SQL) is a standard language for storing, manipulating and retrieving data in databases. SQL is used for storing and managing data in relational database management systems (RDMS).

SQL is one of the most important data science programming languages, as it’s used for performing various operations on the data stored in the databases. The SQL language is widely used today across web frameworks and database applications.

A database is a structured collection of information or data that is often kept electronically in a computer system. The database is usually managed by a database management system (DBMS). Databases are the cornerstone of any software application as this is where we store all of our data. 

A relational database is a database that organizes information into one or more tables. A table is a collection of data organized into rows and columns.

SQL is the most universal and commonly used database language. SQL controls the most commonly used database engines like MySQL, SQL Server, and SQLite. 

Knowing SQL gives you the freedom to explore your data, and by learning SQL, you will also learn concepts that apply to nearly every data storage system.

There are several reasons why you should learn SQL, including:

We live in a data-driven world and data is almost everywhere. Storing and keeping all of that data is only the first step. Managing it and being able to use it is something else. SQL is a highly valuable skill as it enables you to work with the data stored in relational databases. Basic SQL knowledge allows you to accomplish tasks that previously may have been sent to other departments

SQL query syntax uses common English words. Therefore, even if you have no programming experience, you can understand how to use it. There are numerous online resources for learning SQL at all levels (we will look at some of them further down), and many of the entry-level courses are free.

Today we often see large amounts of data being generated on a daily basis. A major benefit of knowing SQL is that you can can extract and manipulate a large volume of data from databases, instead of, for example, browse the database by opening a Excel sheet one after the other

As mentioned above, generally speaking, SQL is an easy language to learn. If you understand programming and already know some other language, I would definitely say that you can learn SQL.

Why it’s easy to learn, I would say that SQL is a logical and systematic language, which is easy to understand and to write once you get the idea of tables, columns, rows, and data types. Additionally, there are some great resources (both free and paid) available online that you can use to learn in your own pace and time.

1. Codecademy

Codecademy is perhaps my favourite resource for learning to code. Codecademy has interactive exercises with immediate feedback. Many of the courses are beginner-friendly and self-paced, giving you the flexibility to learn when it suits you.

Here is the link to check out the course: Learn SQL at Codecademy

2. W3schools

W3schools has text and exercises tutorial that goes through individual SQL functions step by step. I think W3Schools has a straightforward and to the point approach with many great exercises and quizzes.

Here is the link to the SQL Tutorial on W3schools

3. Khan Academy

Khan Academy has great video tutorials with interactive coding challenges. If you’re already familiar with using KhanAcademy, this could be a perfect way to start learning SQL.

Here is the link: Intro to SQL at Khan Academy

4. SQLZoo

SQLZoo is a wiki-based tutorial that provides lessons and projects for beginners in SQL. You will start with the basics and gradually build up to learning how to build intermediate projects

Here is the link to SQLZoo Tutorial

5. Sololearn

Sololearn uses a gamification approach to their learning. You will learn the fundamentals of SQL and how to create, access, and manipulate databases. Sololearn also has a great mobile app that you can use in connection with the website.

Check out the SQL section at Sololearn

1. Datacamp

From the skill track “SQL fundamentals” you will gain the essential skills you need to interact with and query your data in SQL. The course teaches you everything you need to know to start working with databases. If you already know the basics of SQL, you can start at the second or third course in the skill track

Check out the skill track SQL fundamentals at Datacamp

2. Udemy

Udemy has a ton of courses related to SQL (I found over 8000 results by searching for SQL). But, if I would recommend a course on Udemy it would be “The Complete SQL Bootcamp” by Josh Portilla is a great one with top ratings that is an excellent SQL course for beginners.

Although it’s not free, Udemy often has flash sales where you can get the course for under $10. When completed, the course provides a certificate to indicate that you have completed the SQL training, that you can add to your resume or Linkedin profile

Here is the link if you want to check out to The Complete SQL Bootcamp at Udemy and all SQL related courses at Udemy

3. Coursera

Similar to Udemy, Coursera has a ton of great SQL courses (and a lot of other different programming languages and topics). Highlighting one of them would be the SQL for Data Science. One of the best SQL courses on Coursera that teaches you SQL fundamentals and how to work with data. Especially if you are learning SQL for Data Science, then this is the perfect course to start with.

Read more about the course here: SQL for Data Science at Coursera

Some general advice:

• Free resources online: Start with free resources online, they are great. In general, the online resources to learn computer programming are endless, and there’s always tutorial, or blog explanation, that can help you. Then as you progress you can look at the paid resources.
• Take action: Your time and energy should be to start – to take action – not planning and spending too much time decide which resource to use. They majority are good, just pick the one that you think seems nice and you can’t go wrong, and if that would happen, just switch
• Learn by doing. Programming is about solving problems, and the code is your toolbox to solve a problem. To learn how to use that toolbox you must practice, practice and practice, not only watching others do it. So don’t just watch videos and do quizzes, the sooner you start playing with the code, the faster you will learn the given concepts. For example, I had my own project that I used when I learned SQL. It was a database that I built with data related to football, it was a great way for me to learn SQL
• Start with fundamentals: Programming fundamentals always need to come first. The better you understand them, the easier it is to learn the more advanced concepts

When you are starting to explore SQL, you will most likely see the term NoSQL. But are SQL and NoSQL the same thing? No!

As we have already got a good understanding of what SQL is, let’s have short intro to NoSQL and then see some differences between SQL and NoSQL.

NoSQL databases (“not only SQL”) are non-tabular databases and store data differently than relational tables. Some store types of NoSQL databases include column store, document store, key value store, graph store, object store, etc.

Key differences between SQL vs NoSQL:

• Relational: SQL databases are relational, NoSQL databases are non-relational
• Schema: SQL databases utilise structured query language and have a predefined schema. NoSQL databases have dynamic schemas for unstructured data 
• Scalability: SQL are vertically scalable, while NoSQL are horizontally scalable
• Store types: SQL databases are table-based, while NoSQL databases are document, key-value, graph, or wide-column stores
• Aim: SQL databases are better suited for tables and multi-row actions. NoSQL is better for unstructured data like documents or JSON

What is SQL?

SQL is used for storing and managing data in relational database management systems (RDMS) and is one of the most essential data science programming languages. A relational database is a database that organises information into one or more tables.

Why is SQL important and why should I learn it?

SQL is the most universal and commonly used database language. SQL controls the most commonly used database engines like MySQL, SQL Server, and SQLite.  Knowing SQL gives you the freedom to explore your data, and by learning SQL, you will also learn concepts that apply to nearly every data storage system.

Where can I learn SQL?

Best FREE resources to learn SQL
– Codecademy : Learn SQL
– W3schools: SQL Tutorial
– Khan Academy: Intro to SQL
– SQLZoo: SQL Tutorial
– Sololearn: Learn SQL

Best paid resources to learn SQL
– Datacamp: Skill track SQL fundamentals
– Udemy: The Complete SQL Bootcamp
– Coursera; SQL for Data Science