RANK 与 DENSE_RANK的区别:
SQL的帮助文档上讲了不少,可是到底主要的区别什么呢,请先执行下面的两条SQL语句.
注意观察一下就会发现其实就是:Rank如果说有2个排名第一的话,下个排名不是第2.而是第3;DENSE_RANK则相反,如果有2个排名第一,下一个排名还是第2.和生活中的比较相近.
USE AdventureWorks;
GO
SELECT i.ProductID, p.Name, i.LocationID, i.Quantity, RANK() OVER (PARTITION BY i.LocationID order by i.Quantity desc) as RANK
FROM Production.ProductInventory i
JOIN Production.Product p ON i.ProductID = p.ProductID
ORDER BY LocationID
GO
USE AdventureWorks;
GO
SELECT i.ProductID, p.Name, i.LocationID, i.Quantity, DENSE_RANK() OVER (PARTITION BY i.LocationID order by i.Quantity desc) as DENSE_RANK
FROM Production.ProductInventory i
JOIN Production.Product p ON i.ProductID = p.ProductID
ORDER BY LocationID;
GO