write a trigger for stoping dml operations at particular time

As an alternative you could set the database to read only for the time you don't want any dml operations then set it back to read write when it's okay for dml operations.  See this tip for the details on setting a database to read only and read write: http://www.mssqltips.com/sqlservertip/1921/best-practices-for-working-with-read-only-databases-in-sql-server/

Here's an example where you put a trigger on each table that will stop dml whenever a certain value exists in a settings table.

-- create a table where we can specify a row with disable_dml = 1 when we don't want to allow any dml

create table dbo.settings

(

disable_dmlbit

)

go

-- disable dml

insert into dbo.settings values (1)

go

-- create a table for testing

create table dbo.test

(

idint

)

go

-- create a trigger to rollback transaction if dml is disabled

create trigger dbo.test_dml_trigger

on dbo.test

for insert, update, delete

as

begin

if exists (select 'x' from dbo.settings where disable_dml = 1)

begin

raiserror('DML is disabled',16,1)

rollback transaction

return

end

end

go

-- test dml disabled; will display error:

-- Msg 50000, Level 16, State 1, Procedure test_dml_trigger, Line 8

-- DML is disabled

-- Msg 3609, Level 16, State 1, Line 2

-- The transaction ended in the trigger. The batch has been aborted.

begin transaction

insert into dbo.test default values

commit transaction