generate guid for every row in a column

问题:

I Have a stored procedure that has a table with one column and I need to generate a NEWID() for each row in that column. Would I only be able to accomplish this with a loop?

+---+    +--------------------------------------+---+ | a |    | FD16A8B5-DBE6-46AB-A59A-6B6674E9A78D | a | | b | => | 9E4A6EE6-1C95-4C7F-A666-F88B32D24B59 | b | | c |    | 468C0B23-5A7E-404E-A9CB-F624BDA476DA | c | +---+    +--------------------------------------+---+

回答1:

You should be able to select from your table and include the newid() to generate the value for each row:

select newid(), col from yourtable;

See SQL Fiddle with Demo

回答2:

You can create a column with the new guid

alter table yourtable add id varchar(40) not null default NEWID() 

http://sqlfiddle.com/#!3/b3c31/1

回答3:

newid() will definately work. But will also create "fragmented" values.

This may be beneficial or detrimental (think guid as a Primary Key) to your needs.

Here is a procedure I wrote a while back to "kinda help" with fragmentation.

IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[uspNewSequentialUUIDCreateSingle]') AND type in (N'P', N'PC')) DROP PROCEDURE [dbo].[uspNewSequentialUUIDCreateSingle] GO  /*  --START TEST  declare @returnCode int declare @ReturnUUID uniqueidentifier  EXEC @returnCode = dbo.uspNewSequentialUUIDCreateSingle @ReturnUUID output print @ReturnUUID print '/@returnCode/' print @returnCode   --loop test,,,loop exists for TESTING only fyi  declare @counter int select @counter = 1000  while @counter > 0     begin         EXEC @returnCode = dbo.uspNewSequentialUUIDCreateSingle @ReturnUUID output         print @ReturnUUID         select @counter = @counter - 1     end   --END TEST CODE   */  CREATE PROCEDURE [dbo].[uspNewSequentialUUIDCreateSingle] ( @ReturnUUID uniqueidentifier output  --return )  AS   --//You can use NEWSEQUENTIALID() to generate GUIDs to reduce page contention at the leaf level of indexes.  SET NOCOUNT ON   --      declare @ReturnUUID uniqueidentifier  declare @t table ( id int , uuid uniqueidentifier default newsequentialid() ) insert into @t ( id ) values (0) select @ReturnUUID = uuid from @t    SET NOCOUNT OFF GO  GRANT EXECUTE ON dbo.uspNewSequentialUUIDCreateSingle TO public  GO

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