An aggregate function reduces a set of values to a single value. Some of the basic ones are built into SQL, and they are usually fast because optimizers and index structures often store this data for their own use.doi:10.1016/B978-0-12-800761-7.00023-1J. Celko...
The aggregate functions that you can use depend on the type of data that is in the field or expression that you want to use. For more information about the available aggregate functions, see the articleSQL Aggregate Functions. Specifying fields that are not used in an ag...
Aggregate 子句可以用來將彙總函式包含在查詢中。彙總函式會對值集執行檢查及計算,並傳回單一值。您可以使用查詢結果型別的成員來存取計算值。您可以使用的標準彙總函式為 All, Any、Average、Count、LongCount、Max、Min 及 Sum 函式。熟悉 SQL 中彙總的開發人員,一定都熟悉這些函式。本主題的下列章節會加以說明...
When you use the GROUP BY statement, you can use an aggregate function such as SUM, COUNT, or AVG to perform computing on each group. The aggregate function performs computing on each group and returns the aggregate result of computing on all groups. This facilitates the statistical analysis ...
The standard aggregate functions that you can use are the All, Any, Average, Count, LongCount, Max, Min, and Sum functions. These functions are familiar to developers who are familiar with aggregates in SQL. They are described in the following section of this topic.The result of an ...
下列範例示範如何建立對 SQL Server 資料庫執行查詢的新應用程式。 範例會使用 Aggregate 和Group By 子句來計算、加總及平均結果。 如需詳細資訊,請參閱 Aggregate 子句 和Group By 子句。本文中的範例會使用 Northwind 範例資料庫。 若要取得資料庫,請參閱 下載範例資料庫。。
以下示例演示如何创建对 SQL Server 数据库执行查询的新应用程序。 该示例使用Aggregate和Group By子句对结果进行计数、求和与求平均。 有关详细信息,请参阅聚合子句和Group By 子句。 本文中的示例使用 Northwind 示例数据库。 若要获取数据库,请参阅下载示例数据库.。
There are also some SQL statements that perform aggregate functions. You can useSQL COUNTto count the number of rows returned during a SELECT statement,SQL AVERAGEto average out rows returned, andSQL SUMto sum them up. An example of this would be: ...
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For information about aggregate functions, see Aggregate Clause. Consider, for example, a collection of managers and a collection of employees. Elements from both collections have a ManagerID property that identifies the employees that report to a particular manager. The results from a join operation...