[数据库]ROW_NUMBER()OVER函数的基本用法
（1）ROW_NUMBER() OVER(ORDER BY COLUMN) 通常，开发者和管理员在一个查询里，用临时表和列相关的子查询来计算产生行号。现在SQL Server 2005提供了一个函数，代替所有多余的代码来产生行号。 简单的说row_number()从1开始，为每一条分组记录返回一个数字，
（1）ROW_NUMBER() OVER(ORDER BY COLUMN)
通常，开发者和管理员在一个查询里，用临时表和列相关的子查询来计算产生行号。现在SQL Server 2005提供了一个函数，代替所有多余的代码来产生行号。
简单的说row_number()从1开始，为每一条分组记录返回一个数字，这里的ROW_NUMBER() OVER (ORDER
BY xlh DESC) 是先把CourseID列降序，再为降序以后的没条xlh记录返回一个序号。
select ROW_NUMBER() over(order by CourseID desc) as RowIndex,* from
TeacherRoles where ClassCode = '111111111113710401'
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