First_value & Last_Value according to group set is that easy ? tip #44

 

Problem:- 

Most of the time we require data in which we require first value and last value from different group of rows. Now how easy we can get result this is one of the challenge for us.

Solution:-

Lets understand this by an example. Suppose you have a sales table in which you maintain daily sales. Now your want a result sent in which you know what is first sale of the day and what is last sale of the day.

SQL SERVER 2012 provides you facility to achieve this task easily with First_Value & Last_Value function.

The syntax of first_value & Last value is exactly same as Row_Number, Dense_Rank & Rank_function.

See below example in which I have used Adventureworks SalesOrderHeader table.

Now if you see below snap I took a random date 2005-07-12 and fetched record and highlighted is first row & Last Row.

So on date 2005-07-2012 Sales order have 3953.9884 as a frist value and  772.5036 as a second value.

 

Now above specific result  we can achieve by first_Value & Last_Value function of SQL SERVER 2012 as shown below

so, In this way you can achieve the first_Value & last_Value from a group of rows

I hope this may help you somewhere.

Enjoy !!!

RJ

Dense_Rank is exact same but it avoid gaps in ranking TIP#39

 

As discussed in last tip #37 Dense rank having exactly same syntax like Rank the only difference between rank & dense rank is that “dense_Rank fill the gap or avoid gap in ranking means if two row set have same ranking then just after record will have just next ranking.

I am taking same example as we discussed in 27 and using Dense_Rank function.

The syntax is as follow

SELECT  Dense_Rank() OVER (Partition BY column name Order by column name ASC/DESC) , other columns FROM tableName

Now example

 

I will club all this four in next tip and discuss difference.

Enjoy!!

RJ