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{{Short description|Kind of function in SQL}}
In [[SQL]], a '''window function''' or '''analytic function'''<ref name=":1">{{Cite web|title=Analytic function concepts in Standard SQL {{!}} BigQuery|url=https://cloud.google.com/bigquery/docs/reference/standard-sql/analytic-function-concepts|access-date=2021-03-23|website=Google Cloud|language=en}}</ref> is a function which uses values from one or multiple [[Row (database)|rows]] to return a value for each row. (This contrasts with an [[aggregate function]], which returns a single value for multiple rows.) Window functions have an OVER clause; any function without an OVER clause is not a window function, but rather an aggregate or single-row (scalar) function.<ref>{{Cite web|title=Window Functions|url=https://sqlite.org/windowfunctions.html|access-date=2021-03-23|website=sqlite.org}}</ref>
As an example, here is a query which uses a window function to compare each employee with the average salary of their department (example from the [[PostgreSQL]] documentation):<ref>{{Cite web|date=2021-02-11|title=3.5. Window Functions|url=https://www.postgresql.org/docs/13/tutorial-window.html|access-date=2021-03-23|website=PostgreSQL Documentation|language=en}}</ref><syntaxhighlight lang="psql">
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