SQL course [Lesson 1] - Introduction to SQL

in technology •  2 months ago

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What is SQL?


If you are learning or plan to learn programming you will meet the acronym SQL, which stands for Structured Query Language. The main purpose of this language is to get, manipulate and transform data in a relational database.

Due to its simplicity, SQL databases provide safe and scalable storage for millions of websites and mobile applications.

  • There are multiple popular SQL database types, for example SQLite, MySQL, Postgres and Oracle. They all follow the language standards but they differ in some additional features and supported storage types.

If you are going to work with databases there is a very high chance you will need to use SQL so it is a really important language to know.

What does it look like?

Relational databases exist of multiple two-dimensional tables. These consist of rows and columns, similar to Excel spreadsheets.

Example with vehicles:

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Using SQL you will be able to answer specific questions like "What is the type of the vehicle with 2 doors?" or "How many Models does Tesla produce?".

Our first query

Alright, but before writing it we really should now - what is a query?
Queries are statements which describe what data are we looking for.

To retrieve data from a SQL database we need to write SELECT queries. Let's write one to see the the SQL syntax:

SELECT * from vehicles;

The asterisk stands for "all". This query would return all the columns and rows of the vehicles table. Our result would pretty much look like the original table above.

Otherwise this is the way to return only specific columns:

SELECT column, another_column, …
FROM mytable;`

Don't worry we will go deeper into syntax related things in the next lesson, where I will bring further examples for basic querying.

About the course

In this course I will follow and comment sqlbolt's tutorial and do their exercises together with you, sharing the results.

If you would like to fasten up the material or just simply practice by yourself check out their site.

An other suggestion of mine would be to have a look at Sololearn's SQL lessons. This site is also free and you can get a quite solid basic knowledge by completing their material.


Thank you for reading my article!

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{Time spent editing this article: 70 minutes| Word count: 430}


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Added this to my favourites, been using active record but it's nice to have the simple SQL commands available too.

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