clr-user-defined-aggregates.md

title	CLR User-Defined Aggregates
description	SQL Server CLR integration allows you to create custom aggregate functions in managed code, which perform a calculation on a set of values and return a value.
author	rwestMSFT
ms.author	randolphwest
ms.date	03/14/2017
ms.service	sql
ms.subservice	clr
ms.topic	reference
helpviewer_keywords	aggregate functions [CLR integration] custom aggregates [CLR integration] calculations [CLR integration] user-defined functions [CLR integration]

CLR User-Defined Aggregates

[!INCLUDE SQL Server] Aggregate functions perform a calculation on a set of values and return a single value. Traditionally, [!INCLUDEmsCoName] [!INCLUDEssNoVersion] has supported only built-in aggregate functions, such as SUM or MAX, that operate on a set of input scalar values and generate a single aggregate value from that set. [!INCLUDEssNoVersion] integration with the [!INCLUDEmsCoName] .NET Framework common language runtime (CLR) now allows developers to create custom aggregate functions in managed code, and to make these functions accessible to [!INCLUDEtsql] or other managed code.

The following table lists the topics in this section.

Requirements for CLR User-Defined Aggregates
Provides an overview of the requirements for implementing CLR user-defined aggregate functions.

Invoking CLR User-Defined Aggregate Functions
Explains how to invoke user-defined aggregates.