thanks visakh: but my code is very close: it is aggregating to the closest 10 minutes now,just not getting to 15 minutes:here is my code now :IF OBJECT_ID(N'[dbo].[SPNormalizeAddWhen]') IS NOT NULL DROP PROCEDURE [dbo].[SPNormalizeAddWhen]GOCREATE PROCEDURE [dbo].[SPNormalizeAddWhen]Asdeclare @colname nvarchar(20)set @colname='Normalized Add_When'if not exists (select * from syscolumns where id=object_id('Risk') and name=@colname) exec('alter table Risk add [' + @colname + '] datetime')declare @sql nvarchar(500)set @sql='update Risk set [' + @colname + ']=cast(DATEPART(yyyy,[add when]) as nvarchar(4)) + ''-'' + cast(DATEPART(mm,[add when]) as nvarchar(2)) + ''-'' + cast(DATEPART(dd,[add when]) as nvarchar(2)) + '' '' + cast(DATEPART(Hh,[add when]) as nvarchar(2)) + '':'' + cast(round(DATEPART(Mi,[add when]),-1) as nvarchar(2)) 'print @sqlexec(@sql)GO