select `pontos`.`hora_entrada`, `pontos`.`hora_saida`, 
TIMEDIFF(hora_termino, hora_inicio) as total,
TIMEDIFF(hora_saida, hora_inicio) as usado,
if(TIMEDIFF(hora_saida, hora_termino) < "00:00:00", "00:00:00", TIMEDIFF(hora_saida, hora_termino)) as extra,
`agendamentos`.*
from `agendamentos` left join `pontos` on `agendamentos`.`id` = `pontos`.`agendamento_id` 
where `agendamentos`.`medico_id` = 1 and YEAR(agendamentos.data) = 2018 
and MONTH(agendamentos.data) = 11 and `agendamentos`.`deleted_at` is null

-----

SELECT * FROM (
(
select `pontos`.`hora_entrada`, `pontos`.`hora_saida`, 
TIMEDIFF(hora_termino, hora_inicio) as total,
IF(hora_saida is null, "00:00:00", TIMEDIFF(hora_saida, hora_inicio)) as usado,
if((TIMEDIFF(hora_saida, hora_termino) < "00:00:00" or hora_saida is null), "00:00:00", TIMEDIFF(hora_saida, hora_termino)) as extra,
`agendamentos`.*
from `agendamentos` left join `pontos` on `agendamentos`.`id` = `pontos`.`agendamento_id` 
where `agendamentos`.`medico_id` = 1 and YEAR(agendamentos.data) = 2018 
and MONTH(agendamentos.data) = 11 and `agendamentos`.`deleted_at` is null
)as vs
)


BEGIN
#declare horaSaida time default null;
SET @horaSaida := TIMEDIFF(hora_saida, hora_termino); 

if(@horaSaida < time("00:00:00") or @horaSaida is null) then
   SET @horaSaida := time("00:00:00");
end if;

#if(@horaSaida > time("00:00:00")) then
   #SET @horaSaida := "maior";
#end if;
return @horaSaida;
END