Max dans un délai avec des doublons de date

Si j'ai bien compris, vous voulez compter une entrée distincte pour un statut spécifique dans votre période de temps... si c'est le cas, vous devez utiliser le DISTINCT clause dans votre count() passant de count(*) à count(distinct Entry_id)

with c (Status_Id, Entry_Id, Start_Date) AS (
  select Status_Id, Entry_Id, Start_Date from tbl where
  (End_Date BETWEEN '19000101' AND '21000101')
  AND ((Start_Date BETWEEN '19000101' AND '21000101')
  OR End_Date <= '21000101'))
select Status_Id, count(distinct Entry_Id) as cnt from 
 (select Entry_Id, max(start_date) as start_date from c
  group by Entry_Id) d inner join
c on c.Entry_Id = d.Entry_Id
and c.start_date = d.start_date
GROUP BY Status_Id WITH ROLLUP

MODIFIER

Tant que vous ne vous souciez pas du statut renvoyé pour une entrée donnée, je pense que vous pouvez modifier la requête interne pour renvoyer le premier statut et rejoindre également le statut

with c (Status_Id, Entry_Id, Start_Date) AS (
  select Status_Id, Entry_Id, Start_Date from tbl where
  (End_Date BETWEEN '19000101' AND '21000101')
  AND ((Start_Date BETWEEN '19000101' AND '21000101')
  OR End_Date <= '21000101'))
select c.Status_Id, count(c.Entry_Id) as cnt from 
 (select Entry_Id, Start_Date, (select top 1 Status_id from c where Entry_Id = CC.Entry_Id and Start_Date = CC.Start_Date) as Status_Id
  from (select Entry_Id, max(start_date) as start_date from c
  group by Entry_Id) as CC) d inner join
c on c.Entry_Id = d.Entry_Id
and c.start_date = d.start_date
and c.status_id = d.status_id
GROUP BY c.Status_Id

Résultat

Status_id Count
 489       2
 492       1
 495       1