Запретить вставку записи

set nocount on;
go
 
drop table if exists #t, #all_data;
go
 
create table #t (a int, b int, c int, time_diff bigint not null default datediff_big(millisecond, '2000', sysdatetime()) / 1000);
create unique index UQ_a_b_c_time_diff on #t (a, b, c, time_diff) with (ignore_dup_key = on);
 
create table #all_data (a int, b int, c int, time_diff bigint not null default datediff_big(millisecond, '2000', sysdatetime()) / 1000);
 
go
 
declare @c int = 0, @msg varchar(100);
 
while @c < 100
begin
    insert into #t (a, b, c) values (1, 1, 1);
    insert into #all_data (a, b, c) values (1, 1, 1);
    waitfor delay '00:00:00:100';
 
    set @msg = formatmessage('@c = %s', cast(@c as varchar(100)));
    raiserror(@msg, -1, -1) with nowait;
    set @c += 1;
end;
 
select * from #t;
select * from #all_data order by time_diff;

create unique index UQ_a_b_c_time_diff on #t (a, b, c, time_diff) with (ignore_dup_key = on (suppress_messages = on));