Skip to main content

NEWID vs NEWSEQUENTIALID

Some pointers:

1. NewSequentialID() and NewID() both generates the GUID of datatype of uniqueidentifier.
2. NewID() generates the GUID in random order
3. NewSequentialID() generates the GUID in sequential order.
4. NewSequentialID() can be used ONLY in default clause of a table.
5. NewSequentialID() is easily predictable
6. So if security is a major concern then go for NewID() instead of NewSequentialID().

Example to demonstrate NEWSEQUENTIALID():

Create table #tblDemoSequentialID
(
Column1 uniqueidentifier default NewID(),
Column2 uniqueidentifier default NewSequentialID(),
Fname varchar(30)
)

Pump-in few dummy records:

Insert into #tblDemoSequentialID (Fname) values ('Vadivel')
Insert into #tblDemoSequentialID (Fname) values ('Rajinikanth')
Insert into #tblDemoSequentialID (Fname) values ('Sivaji')

In this query 'Column1' would demonstrate that the 'NEWID' has generated GUID in random fashion. Also 'Column2' would contain GUID in Sequential Order (refer the below screenshot).

Select Fname as [First Name], Column1 as [NewID], Column2 as [NewSequentialID] from #tblDemoSequentialID



Flush the table and proceed to next demo:

Delete from #tblDemoSequentialID

Create another temp table:

Create table #tblDemoTWO
(
LName varchar(20),
Column_SeqID uniqueidentifier default NewSequentialID()
)

Lets insert data into both these tables alternatively. This is to prove that the NewSequentialID would be in sequential order :)

Insert into #tblDemoSequentialID (Fname) values ('VDSI')
Insert into #tblDemoTWO (Lname) values ('Yuvaraj')

Insert into #tblDemoSequentialID (Fname) values ('Verizon')
Insert into #tblDemoTWO (Lname) values ('India')

Insert into #tblDemoSequentialID (Fname) values ('Dhoni')
Insert into #tblDemoTWO (Lname) values ('Mahendra')

Select Fname as [First Name], Column1 as [NewID], Column2 as [NewSequentialID] from #tblDemoSequentialID where [Fname] in ('VDSI', 'Verizon', 'Dhoni')

Select Lname as [Last Name], Column_SeqID as [NewSequentialID] from #tblDemoTWO

Just go through the output of both the above queries. You could find it for yourself that the NewSequentialID columns in both the tables got incremented sequentially.

Clean up :

Drop table #tblDemoSequentialID
Drop table #tblDemoTWO
Go
Labels:

Comments

Post a Comment

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 ...
8 comments
Read more

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...
40 comments
Read more

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...
2 comments
Read more