COUNT with DISTINCT Window

COUNT with DISTINCT Window is a SQL function in the Aggregate Functions category. Windowed COUNT DISTINCT counts unique values per partition without collapsing rows. The syntax is COUNT(DISTINCT col) OVER (PARTITION BY grp). It accepts DISTINCT col. It returns distinct count window. A close relative is COUNT(), which returns the number of rows (or non-NULL values) in a group. A close relative is SUM(), which returns the sum of all non-NULL values in a group. Works with numeric columns. A close relative is AVG(), which returns the average (mean) of all non-NULL values in a group. More about this category: Aggregation functions — COUNT, SUM, AVG, MIN, MAX, GROUP BY, HAVING. Related Aggregate Functions entries: COUNT(), SUM(), AVG(), MIN(), MAX(), GROUP_CONCAT() / LISTAGG(), STRING_AGG(), VARIANCE() / VAR_SAMP(). This page is part of the free SQL Reference documentation covering 762+ statements, functions, and clauses, each with syntax, parameters, return values, and examples for MySQL, PostgreSQL, SQL Server, and SQLite.