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 GuidNo
generates FBF2D8E9-F8BE-4F0B-9D49-7CA7C2E3F22C on my machine
Generate only digits :
SELECT ABS(CAST(CAST(NEWID() AS VARBINARY(5)) AS Bigint)) as UniqueNo
generates 427357674589 on my machine
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),13),0,0)
generates 470370453006 on my machine