Skip to main content

Alternate rows ...

Sometime back in a user group a guy enquired "how to fetch alternate rows from a SQL Server table"?

As all of us know there isn't any direct method of doing it in SQL Server. So let me explain couple of work arounds for this.

Using Table Variables

Declare @tmpTable table
(
 [RowNum] int identity,
 [au_id] varchar(50) NOT NULL ,
 [au_lname] [varchar] (40),
 [au_fname] [varchar] (20),
 [phone] [char] (12)
)

-- Filling the row number column of the table variable
Insert into @tmpTable select au_id,au_lname, au_fname, phone from authors

-- Fetching the alternate records from the table.
Select * from @tmpTable where RowNum % 2 <> 0

Using Temp Tables

-- Filling the row number column of the temp table
Select IDENTITY(int, 1,1) RowNum, au_id,au_lname, au_fname, phone INTO #tmpTable from authors

-- Fetching the alternate records from the table.
Select * from #tmpTable where RowNum % 2 <> 0

Obviously we could solve this using many other methods like using cursors, using user defined functions etc., Just think about performance hit before choosing a method.

Comments

Bravo, your idea it is magnificent

Popular posts from this blog

[Non Tech] Want to know the recipe for Omelette :)

Fed up with Bread - Jam and Curd Rice, today i wanted to eat Omelette. Interesting part is I wanted to cook it myself :) So in the first picture you see all the items which are needed for preparing an Omelette. When I had a closer look at the eggs I see that almost all the eggs are broken. But believe me when I bought it couple of days back it was in perfect condition! I was wondering whether the eggs have become rotten or pretty old to consume! I tried taking an egg and break it but couldn't break it at all :) Since I have kept in the freezer all the eggs have frozen and looked like a iron ball :) After trying for few minutes of trying i removed the shell of the egg and then kept that iron ball :) into a bowl and placed it within Oven. I heated it for 1 minute and checked. It melted only to a limit. So i just set it for another 2 minutes and checked it later. It has melted but the part of the egg white has become a Omelette :( I didn't leave it there. I took the bowl out of ...

Script table as - ALTER TO is greyed out - SQL SERVER

One of my office colleague recently asked me why we are not able to generate ALTER Table script from SSMS. If we right click on the table and choose "Script Table As"  ALTER To option would be disabled or Greyed out. Is it a bug? No it isn't a bug. ALTER To is there to be used for generating modified script of Stored Procedure, Functions, Views, Triggers etc., and NOT for Tables. For generating ALTER Table script there is an work around. Right click on the table, choose "Modify" and enter into the design mode. Make what ever changes you want to make and WITHOUT saving it right click anywhere on the top half of the window (above Column properties) and choose "Generate Change Script". Please be advised that SQL Server would drop actually create a new table with modifications, move the data from the old table into it and then drop the old table. Sounds simple but assume you have a very large table for which you want to do this! Then it woul...

My Wedding Anniversary :)

Six years back on the same day I married Sai Lakshmi (12-July-2000). I know Sai for almost 13 years now :) I fell in love with her during my 12th standard. I know @ 17 yrs any person wouldn't be matured enough to make a big decision like this. But thank God my choice was perfect :) Even now, very often we used to think about the past and laugh at our behaviors/actions then. My love story would be really interesting (at least for me and Sai :)) and I am sure none of you guys would be interested in reading about it so lemme not get into it in-depth. But one thing which I want to share is "Without Sai, I wouldn't have entered into the IT field at all". She was instrumental in convincing me to study my Master's degree in Computer Application. That's the move that changed my career. Till my schooling, my dream was to either become a "big" sportsman (Cricket and Badminton were my favorites at that time.) or an Aeronautics engineer. Unfortunately, my l...