SQL Server 2019

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.
create table Limittime(
  ID int
  ,Times datetime
)
insert into Limittime(
  ID,Times
)
select isNull((select max(ID) from Limittime),0) + 1 as ID
,GetDate() Times
where exists(
  select 0
  from Limittime
  where datediff(minute,Times,GetDate()) < 15
  having count(0) <= 1
)
1 rows affected

select *
from Limittime


ID
Times


1
2023-05-03 15:10:55.283


insert into Limittime(
  ID,Times
)
select isNull((select max(ID) from Limittime),0) + 1 as ID
,GetDate() Times
where exists(
  select 0
  from Limittime
  where datediff(minute,Times,GetDate()) < 15
  having count(0) <= 1
)
1 rows affected

select *
from Limittime


ID
Times


1
2023-05-03 15:10:55.283

2
2023-05-03 15:10:55.300


insert into Limittime(
  ID,Times
)
select isNull((select max(ID) from Limittime),0) + 1 as ID
,GetDate() Times
where exists(
  select 0
  from Limittime
  where datediff(minute,Times,GetDate()) < 15
  having count(0) <= 1
)
select *
from Limittime


ID
Times


1
2023-05-03 15:10:55.283

2
2023-05-03 15:10:55.300