What is GUID ? How to generate a GUID ?

Posted Date: 11 Mar 2004	Resource Type: Articles	Category: General
Author: Tony John	Member Level: Diamond
Rating:	Points: 10

GUID stands for Globally Unique IDentifier. It is a string of
numbers and/or letters.

A GUID represents a Unique identifier - means you cannot generate the same GUID
more than once. A GUID has a very low (...practically impossible) probability of being duplicated

GUIDs have a variety of applications. You can use a GUID as a primary
key in your database table or in a several other scenarios. A good
example would be, if you have a distributed application where data is
generated and stored in various locations and you want to merge all those
data at some intervals of time, you may use GUID as the primary key.

GUIDs can be generated in a number of ways; most often a hash of
several things that might be unique at any given point in time like the IP
address plus the clock date/time etc are used to generate Unique Ids.
Each system may have slightly different algorithm to generate the Unique
Id.

In .net, you can use the System.Guid class to generate a GUID. See the
following sample code :


System.Guid  guid = System.Guid.NewGuid ();
String id = guid.ToString();

System.Guid.NewGuid () returns a Guid object. You can use the
.ToString() method to convert it to a string. In the above example, you may get
a string which look like the following:


"b91c9121-0a17-4b26-a09d-d5980eb532db"

Can anyone generate the same Guid as shown above ? Try your luck !!

Responses

Author: Abhinav 18 Sep 2004 Member Level: Bronze Points : 0

It helped me a lot. i got an idea abt how to avoid multiple savings

Author: Sagar Laddha 12 Mar 2009 Member Level: Bronze Points : 1

Why can't the same GUID be generated? Is it just because of the huge number of possible values or because it is a combination of the algorithm?

Author: greeny_1984 13 Mar 2009 Member Level: Diamond Points : 2

hi,

you have mentioned

"A good
example would be, if you have a distributed application where data is
generated and stored in various locations and you want to merge all those
data at some intervals of time, you may use GUID as the primary key."

can you eleborate more on how to achieve this with a example

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