SQL Server 2012 开窗函数

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— 开窗函数：在结果集的基础上进一步处理(聚合操作)

— Over函数,添加一个字段显示最大年龄

SELECT * ,

MAX(StuAge) OVER ( ) MaxStuAge

FROM dbo.Student;

— Over函数,添加一个字段显示总人数

SELECT * ,

COUNT(StuID) OVER ( ) StuCount

FROM dbo.Student;

— Partition By 分组统计数量

— 根据性别分组后，统计

SELECT COUNT(*) OVER ( PARTITION BY StuSex ) ,

*

FROM dbo.Student;

— 根据班级分组后，统计、排序

SELECT COUNT(*) OVER ( PARTITION BY Class ORDER BY Height) ,

*

FROM dbo.Student;

— Over函数,添加一个字段显示平均身高

SELECT * ,

AVG(Height) OVER ( ) AgeHeight

FROM dbo.Student;

–Row_Rumber()

SELECT ROW_NUMBER() OVER ( ORDER BY StuID DESC ) RowNumber ,

*

FROM dbo.Student

–Row_Rumber() 实现分页效果

;

WITH T AS ( SELECT ROW_NUMBER() OVER ( ORDER BY StuID DESC ) RowNumber ,

*

FROM dbo.Student

)

SELECT *

FROM T

WHERE T.RowNumber BETWEEN 1 AND 3;

–Rank() 排名函数,名次相同，跳过

SELECT RANK() OVER ( ORDER BY Height ) ,

*

FROM dbo.Student;

–DENSE_Rank() 排名函数，名次相同不跳过

SELECT DENSE_RANK() OVER ( ORDER BY Height ) ,

*

FROM dbo.Student;

— NTILE()函数，参数：记录总数/划分区域 = 每个区域数组，把记录序号放进数组 (平均分组)

SELECT NTILE(3) OVER ( ORDER BY StuSex ) ,

*

FROM dbo.Student;