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SQL Tutorial: A Guide to SQL Queries
Structured Query Language, better known as SQL, is the standard language used to communicate with relational databases
Introduction
Whether you’re a data analyst pulling numbers for a report, a backend developer storing user information, or a data scientist preparing a dataset for machine learning, SQL is likely to be one of the first tools you reach for. It has been around since the 1970s, and despite the constant churn of new programming languages and frameworks, SQL has remained remarkably stable and universally useful.
This guide is designed to take you from the fundamentals of SQL all the way through to more advanced querying techniques. We’ll cover how databases are structured, how to retrieve and filter data, how to combine data from multiple tables, how to modify data, and how to use some of SQL’s more powerful features like window functions and common table expressions. Along the way, you’ll see plenty of practical examples that you can adapt to your own projects.
By the end of this article, you should be comfortable writing SQL queries that answer real questions about real data.
