Max of Row Number Logic

Question

Hi,
Below are my table structure
create table Test (ProductId int primary key identity(1,1), productnumber varchar(50),productname varchar(50),Quantity int)
insert into Test values('PN1001','Pepsi',20),
('PN1001','curd',2),
('PN1001','Noodles',10),
('PN1001','Shrimp',40),
('PN1002','Mango',10),
('PN1002','Pizza',5),
('PN1002','Soup',10),
('PN1002','Honey',30),
('PN1001','Pepsi',15),
('PN1001','Curd',50),
('PN1001','Noodles',13),
('PN1001','Shrimp',32),
('PN1002','Mango',11),
('PN1002','Pizza',14),
('PN1002','Soup',18),
('PN1002','Honey',20)
I need to take the last inserted set of records. unfortunately i don't have created date in my table and not sure why it hasn't created
when the guy build the table schema. i know this is poor table structure cannot do anything at the moment.
Me required output :
select 'PN1001' as productnumber,'Pepsi' as productname,15 as Quantity union all
select 'PN1001' as productnumber,'curd' as productname,50 as Quantity union all
select 'PN1001' as productnumber,'Noodles' as productname,13 as Quantity union all
select 'PN1001' as productnumber,'Shrimp' as productname,32 as Quantity union all
select 'PN1002' as productnumber,'Mango' as productname,11 as Quantity union all
select 'PN1002' as productnumber,'Pizza' as productname,14 as Quantity union all
select 'PN1002' as productnumber,'Soup' as productname,18 as Quantity union all
select 'PN1004' as productnumber,'Honey' as productname,20 as Quantity
ie. The logic i need to achieve is to get the last insert records based on productnumber.
This is my try
;with TotalRecords as (
select ROW_NUMBER() OVER
(PARTITION BY productnumber
Order BY productnumber DESC )
AS RowNumber,productnumber, productname,Quantity from Test)
select * from TotalRecords
please Note : on this sample i can specify Rownumber = 3 to get
latest records. but i should not do that because i don't need to specify the particular number as it can change any time. so please help me achieving my requiement
Any sample query please 
loving dotnet

Answer 1

That you for trying to post DDL, but you failed. This is not a proper schema. Why do you think that IDENTITY is ever used in RDBMS?? This proprietary feature is a physical table property. It count the insertion attempts on one table, in one SQL Server
data base on one machine. This is as silly as identifying an automobile by the current parking space number in on garage in one building. NO! You use the VIN. 
Your guy screwed you completely and you are dead. 
He do not even know the differences between a row and record. He did not normalize. Why don't you people know that products have industry standard code? The current direction in retail is the GTIN; do the research your people skipped. 
CREATE TABLE Product_Test 
(product_gtin CHAR(15) NOT NULL
   REFERENCES Products (product_gtin)
   ON UPDATE CASCADE,
 stock_date DATE DEFAULT CURRENT_TIMESTAMP NOT NULL,
 product_qty INTEGER NOT NULL CHECK (product_qty > 0))
 PRIMARY KEY (product_gtin, stock_date));
CREATE TABLE Products
(product_gtin CHAR(15) NOT NULL PRIMARY KEY, 
 product_name VARCHAR(50) NOT NULL);
See how DRI actions do the work for you? 
>> I need to take the last inserted set of records [sic]. <<
Another huge misconception! A table is a set; a set has no ordering. This is explained the first day of any RDBMS class. The second day, he should have gotten The Information Principle; any relationship is modeled with scalar values in the columns of a table.
That is why we need a stock date. 
>>  Unfortunately I don't have creation date in my table and not sure why it hasn't created when the guy build the table schema. I know this is poor table structure cannot do anything at the moment. <<
The date ought to the stocking date for the products, not the creation date of the physical row in the table! See the difference? Your mindset is still not up to a logical data model. 
Can you kill this idiot? We cannot help you with this! We have no way to be sure that the rows logical ordering is the same as some physical ordering. 
--CELKO-- Books in Celko Series for Morgan-Kaufmann Publishing: Analytics and OLAP in SQL / Data and Databases: Concepts in Practice Data / Measurements and Standards in SQL SQL for Smarties / SQL Programming Style / SQL Puzzles and Answers / Thinking
in Sets / Trees and Hierarchies in SQL