iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
SQL stands for Structured Query Language. It is the standardized language used to define, retrieve, and change data in relational database systems.
What is SQL used for?
SQL lets people and software work with the structure and contents of a relational database. It can define database structures, add or change data, and retrieve information. The PostgreSQL 17 manual, for example, groups SQL topics around creating structures, populating a database, querying data, and working with data types and functions.
SQL is a language, not a database product. PostgreSQL, MySQL, and SQL Server are examples of database systems that implement SQL.
How does a SQL query work?
Relational databases organize data into tables, which contain rows and columns. A SQL statement can request particular information from a table. For example:
#1 Best Overall
SELECT name FROM customers;This asks for the name values in the customers table. It is a simple illustration; SQL features and syntax can differ among database systems. Also, without an explicit sort, a query does not guarantee the order of returned rows, as PostgreSQL’s tutorial explains.
Is SQL a standard?
Yes. SQL’s formal standard is ISO/IEC 9075, titled “Database Language SQL.” PostgreSQL’s documentation identifies the 2023 edition as ISO/IEC 9075:2023, also known as SQL:2023.
The standard gives SQL a common foundation, but it does not mean every database supports precisely the same features. Products may implement different portions of the standard and add their own extensions. PostgreSQL’s documentation specifically notes that some of its SQL features are extensions, so check the documentation for the database you use when a particular feature matters.
Free tools Windows power users keep installed
One-click scans. No signup required.
Where did SQL come from?
According to PostgreSQL’s archived historical account, Donald Chamberlin and colleagues at IBM Research defined SEQUEL (Structured English Query Language) in 1974. The account says a later revision was renamed SQL, ANSI ratified an SQL standard in 1986, and ISO accepted it in 1987. These dates are presented as PostgreSQL’s historical account, rather than as a direct statement from IBM or a standards body.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
