How to Generating Unique Identifire in SQL Server

We often find ourselves in the need of generating unique numbers in our database applications.

Let us quickly take a tour of how to do that using Sql server 2005.

SQL Server contains the NEWID() function. This function creates a unique value of type uniqueidentifier. We can use this function in several ways to generate unique numbers to suit our requirements :

Generate GUID's :

UniqueIndentifiers are also knows as GUID's. To generate a GUID use :

SELECT NEWID() as Guid

generates e00ab1d2-7484-410b-a55a-bcfa131a727e on my machine

Generate only digits :

SELECT ABS(CAST(CAST(NEWID() AS VARBINARY(5)) AS Bigint)) as UniqueNo

generates 427357674589

Generate fixed digit unique numbers :

At times, we may also need to generate fixed digit numbers. You can do that in the following manner :

SELECT REPLACE(STR(CAST(CAST(NEWID() AS binary(5)) AS bigint),12),0,0)