SQL Server 排名函数 简单应用

--排名函数 ROW_NUMBER()  RANK(), DENSE_RANK(),NTILE() 
 
 
Over()函数 为排名函数生成排序顺序、
 select ROW_NUMBER() over(order by OrderDate) 
  as Romber,SalesOrderID,OrderDate
  from SalesLT.SalesOrderHeader
  
  ---创建一个单一的排序
  SELECT ROW_NUMBER() OVER(partition by year(OrderDate),Month(OrderDate) order by orderdate) as rownumber,
  SalesOrderID,OrderDate,ShipMethod
    FROM SalesLT.SalesOrderHeader 
  WHERE SalesOrderID>=280 ORDER BY OrderDate;
  
  ---ROW_NUMBER()
  
  SELECT rowNumber ,SalesOrderNumber SalesOrderID,OrderDate  from (
  select ROW_NUMBER() over(order by orderdate,SalesOrderID)
  as rowNumber,* from 
  SalesLT.SalesOrderHeader 
  where SalesOrderID>293
  ) as Q  where 
  rowNumber between 21 and 40
  order by rowNumber;
  
  --Rank()  DENSE_RANK()  EG:例如 张三跟王五 都是第二名 那么他们的Rank的值应为2
  
   select productID,COUNT(*) as 'Count'
   from SalesLT.SalesOrderDetail 
   group by ProductID
   order  by COUNT(*);
   
  select Productid,salescount,RANK() over(order by salescount) as 'Ranks',
  DENSE_RANK() OVER(ORDER BY salescount) AS 'Dense_rank' from (select ProductID,COUNT(*) as salescount  from SalesLT.SalesOrderDetail
  group by ProductID) as Q  group by 'Ranks';
  
  运行结果：对比

通过 对比：Rank的结果与 DeseRank的结果不一样。。