-- 開窗函數：在結果集的基礎上進一步處理(聚合操作)
-- Over函數,添加一個字段顯示最大年齡
SELECT * ,
    MAX(StuAge) OVER ( ) MaxStuAge
FROM  dbo.Student;
-- Over函數,添加一個字段顯示總人數
SELECT * ,
    COUNT(StuID) OVER ( ) StuCount
FROM  dbo.Student;
-- Partition By 分組統計數量
-- 根據性別分組后，統計
SELECT COUNT(*) OVER ( PARTITION  BY StuSex ) ,
    *
FROM  dbo.Student;
-- 根據班級分組后，統計、排序
SELECT COUNT(*) OVER ( PARTITION  BY Class ORDER BY Height) ,
    *
FROM  dbo.Student;
-- Over函數,添加一個字段顯示平均身高
SELECT * ,
    AVG(Height) OVER ( ) AgeHeight
FROM  dbo.Student;
--Row_Rumber()
SELECT ROW_NUMBER() OVER ( ORDER BY StuID DESC ) RowNumber ,
    *
FROM  dbo.Student
--Row_Rumber() 實現分頁效果
;
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() 排名函數,名次相同，跳過
SELECT RANK() OVER ( ORDER BY Height ) ,
    *
FROM  dbo.Student;
--DENSE_Rank() 排名函數，名次相同不跳過
SELECT DENSE_RANK() OVER ( ORDER BY Height ) ,
    *
FROM  dbo.Student;
-- NTILE()函數，參數：記錄總數/劃分區域 = 每個區域數組，把記錄序號放進數組 (平均分組)
SELECT NTILE(3) OVER ( ORDER BY StuSex ) ,
    *
FROM  dbo.Student;