Autoincrement uniqueidentifier in C#

Question

Basically I want to use uniqueidentifier in similar way as identity. I don't want to insert values into it, It should just insert values automatically, different value for each row. I'm not able to set autoincrement on columns of type uniqueidentifier(the property 'autoincrement' is set to false and is not editable).

Answer 1

Use NewID() as the default value. At least this is what you would do for SQL Server.

Answer 2

Or even better: use the newsequentialid() as the default for your UNIQUEIDENITIFER column. That'll give you a somewhat sequential series of GUIDs.

CREATE TABLE dbo.YourTable   
   (SerialID UNIQUEIDENTIFIER 
        CONSTRAINT DF_SerialID DEFAULT newsequentialid(),
     .... (other columns)......
   )

Trouble is: newsequentialid is only available as a column default - you cannot call it as a function or anything. But that seems to fit your requirements.

UPDATE: there appears to be an acknowledged bug in SQL Server Management Studio that prevents specifying newsequentialid() as the default for a column in the interactive table designer.

See: http://social.msdn.microsoft.com/Forums/en-US/sqltools/thread/cad8a4d7-714f-44a2-adb0-569655ac66e6

Workaround: create your table without specifying any default, and then type in this T-SQL statement in a normal query window and run it:

ALTER TABLE dbo.YourTable
    ADD CONSTRAINT DF_SerialID DEFAULT newsequentialid() FOR SerialID

That should do the trick!

Answer 3

The lame thing about newsequentialid is that its only sequential until the sql server service restarts. WTF? Thats super lame.

Answer 4

I guess you mean in SQLServer and not C#...

Set the column as PRIMARY KEY and ROWGUID