Structured Query Language: the standard language for storing, querying, and managing data in relational databases.
SQL lets you describe what data you want, and the database figures out how to get it. Core commands include SELECT to read data, INSERT to add rows, UPDATE to change them, and DELETE to remove them. JOIN combines related tables, for example linking orders to the customers who placed them, while GROUP BY with functions like COUNT and SUM produces summaries.
SQL was developed at IBM in the 1970s and is supported by databases such as PostgreSQL, MySQL, SQLite, Microsoft SQL Server, and Oracle, as well as cloud data warehouses. Each system adds its own extensions, but the fundamentals are shared. SQL remains one of the most valuable skills for analysts, developers, and data engineers.
A system that stores cleaned, structured data from many sources, optimized for reporting and business analysis.
NoSQLA broad category of databases that store data in formats other than traditional relational tables, such as documents, key-value pairs, or graphs.
QueryA request for data or information from a database, search engine, or other system, usually written in a specific language or format.
Relational DatabaseA database that stores data in tables of rows and columns and links related tables through shared keys, usually queried with SQL.
SQL InjectionAn attack in which malicious input is inserted into a database query, tricking the application into exposing or altering data.
A step-by-step software engineering roadmap with skills, milestones and realistic timelines, plus how to land your first developer role with or without a degree.
A month-by-month plan to learn to code for free with freeCodeCamp, The Odin Project, CS50x and MDN, plus projects that keep you accountable.
SQL vs NoSQL explained by data shape and access pattern, with concrete examples for relational, document, key-value, wide-column and graph databases.