SQL Server 2012 - 开窗函数
- -- 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;
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