SQL Server 2022

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declare @dt datetime

set @dt = '09-22-2007 15:07:38.850'
select convert(varchar(16),dateadd(SECOND,30,@dt),120) nearest_minute

nearest_minute

2007-09-22 15:08

declare @dt datetime
set @dt = '09-22-2007 15:07:28.850'
select convert(varchar(16),dateadd(SECOND,30,@dt),120) nearest_minute

nearest_minute

2007-09-22 15:07

declare @dt datetime
set @dt = '09-22-2007 15:07:38.850'
select convert(varchar(13),dateadd(MINUTE,30,@dt),120) nearest_hour

nearest_hour

2007-09-22 15

declare @dt datetime
set @dt = '09-22-2007 15:30:28.850'
select convert(varchar(13),dateadd(MINUTE,30,@dt),120) nearest_hour

nearest_hour

2007-09-22 16