¿Puedo hacer que SQL Server llame a un proceso almacenado cada n segundos?

Use un temporizador y activación . Ningún proceso externo, sigue funcionando después de una conmutación por error de agrupación en clúster o duplicación, sigue funcionando incluso después de una restauración en una máquina diferente y también funciona en Express.

-- create a table to store the results of some dummy procedure
create table Activity (
    InvokeTime datetime not null default getdate()
    , data float not null);
go  

-- create a dummy procedure
create procedure createSomeActivity
as
begin
    insert into Activity (data) values (rand());
end
go

-- set up the queue for activation
create queue Timers;
create service Timers on queue Timers ([DEFAULT]);
go

-- the activated procedure
create procedure ActivatedTimers
as
begin
declare @mt sysname, @h uniqueidentifier;
begin transaction;
    receive top (1)
        @mt = message_type_name
        , @h = conversation_handle
        from Timers;

    if @@rowcount = 0
    begin
        commit transaction;
        return;
    end

    if @mt in (N'http://schemas.microsoft.com/SQL/ServiceBroker/Error'
        , N'http://schemas.microsoft.com/SQL/ServiceBroker/EndDialog')
    begin
        end conversation @h;
    end
    else if @mt = N'http://schemas.microsoft.com/SQL/ServiceBroker/DialogTimer'
    begin
        exec createSomeActivity;
        -- set a new timer after 2s
        begin conversation timer (@h) timeout = 2;
    end
commit
end
go

-- attach the activated procedure to the queue
alter queue Timers with activation (
    status = on
    , max_queue_readers = 1
    , execute as owner
    , procedure_name = ActivatedTimers);
go  


-- seed a conversation to start activating every 2s
declare @h uniqueidentifier;
begin dialog conversation @h
    from service [Timers]
    to service N'Timers', N'current database'
    with encryption = off;
begin conversation timer (@h) timeout = 1;

-- wait 15 seconds
waitfor delay '00:00:15';

-- end the conversation, will stop activating
end conversation @h;
go

-- check that the procedure executed
select * from Activity;