SQL Server-fråga för att gruppera sekventiella datumdata

Först lite testdata:

create table seasons (seasonId int primary key
    , "date" datetime not null unique
    , tariffId int not null)

insert into seasons values (1, '2009-01-01', 1)
insert into seasons values (2, '2009-01-02', 1)
insert into seasons values (3, '2009-01-03', 2)
insert into seasons values (4, '2009-01-04', 3)
insert into seasons values (5, '2009-01-05', 3)
insert into seasons values (6, '2009-01-06', 1)
insert into seasons values (7, '2009-01-07', 1)
insert into seasons values (8, '2009-01-08', 3)
-- add a tarrif with a datespan larger than 2
insert into seasons values (9, '2009-01-09', 4)
insert into seasons values (10, '2009-01-10', 4)
insert into seasons values (11, '2009-01-11', 4)

Bygg på Dave Barkers svar och lägg till row_number() inom de inline-vyerna så att vi vet vilket som är det första min-värdena, vilket är det andra, etc. genom tariffId. (Faktiskt eftersom ett datum inte kan ha mer än ett tariffId, behöver vi inte dela upp efter tariffId.)

SELECT MinValues.Seasonid, MinValues.Date, MaxValues.Date, MaxValues.tariffid 
FROM (
    SELECT *, row_number() over (partition by tariffId order by "date") as RN 
      FROM [dbo].[Seasons] tbl1
     WHERE NOT EXISTS (SELECT * 
                         FROM [dbo].[Seasons] tbl2 
                        WHERE tbl1.seasonid - tbl2.seasonid = 1 
                          AND tbl1.tariffId = tbl2.tariffId)) as minValues
JOIN (
     SELECT *, row_number() over (partition by tariffId order by "date") as RN
       FROM [dbo].[Seasons] tbl1
      WHERE NOT EXISTS (SELECT *
                          FROM [dbo].[Seasons] tbl2 
                         WHERE tbl2.seasonid - tbl1.seasonid = 1 
                           AND tbl1.tariffId = tbl2.tariffId)) as maxValues
ON MinValues.TariffId = MaxValues.tariffId
and MinValues.RN = MaxValues.RN
order by MinValues.Date

Resultat:

1   2009-01-01 00:00:00.000 2009-01-02 00:00:00.000 1
3   2009-01-03 00:00:00.000 2009-01-03 00:00:00.000 2
4   2009-01-04 00:00:00.000 2009-01-05 00:00:00.000 3
6   2009-01-06 00:00:00.000 2009-01-07 00:00:00.000 1
8   2009-01-08 00:00:00.000 2009-01-08 00:00:00.000 3
9   2009-01-09 00:00:00.000 2009-01-11 00:00:00.000 4