SQL stands for [Structured Query Language](https://en.wikipedia.org/wiki/SQL) and is used for retrieving and manipulating data in a relational database management system (RDBMS). SQL is a [declarative language](https://en.wikipedia.org/wiki/Declarative_programming) meaning you don't tell the computer how to return the data, you tell it what you want the results to look like and the database figures out the best way to deliver those results. ## [SQL Variants](http://troels.arvin.dk/db/rdbms/) There are multiple variants or dialects of SQL built by different companies which are built on top of the SQL Standard. They are roughly 95% similar in terms of syntax but each database may interpret them differently leading to optimization differences between databases. It's typically not important to learn more than one, especially when you are just getting started. However, when you get more advanced it will be helpful to know the differences as you will likely start using different types of databases for different use cases. The most common variants are: - [[T-SQL]] ([[Microsoft SQL Server]]) - [[PostgreSQL]] ([[PostgreSQL]]) - [[MySQL]] ([[MySQL]]) ![[Learning Resources#SQL Learning Resources]] # [Recent Posts](https://www.reddit.com/r/dataengineering/search/?q=sql&restrict_sr=1&t=year&sort=relevance) %% wiki footer: Please don't edit anything below this line %% ## This note in GitHub <span class="git-footer">[Edit In GitHub](https://github.dev/data-engineering-community/data-engineering-wiki/blob/main/Tools/Programming%20Languages/SQL.md "git-hub-edit-note") | [Copy this note](https://raw.githubusercontent.com/data-engineering-community/data-engineering-wiki/main/Tools/Programming%20Languages/SQL.md "git-hub-copy-note")</span> <span class="git-footer">Was this page helpful? [👍](https://tally.so/r/mOaxjk?rating=Yes&url=https://dataengineering.wiki/Tools/Programming%20Languages/SQL) or [👎](https://tally.so/r/mOaxjk?rating=No&url=https://dataengineering.wiki/Tools/Programming%20Languages/SQL)</span>