SQL Server 2019

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select *
into t
from (values 
             ('Ball', 'Red', convert(date, '2020-01-01'), convert(date, '2020-03-24')),
             ('Ball', 'Blue', convert(date, '2020-03-25'), convert(date, '2020-04-12')),
             ('Ball', 'Blue', convert(date, '2020-04-13'), convert(date, '2020-05-07')),
             ('Ball', 'Blue', convert(date, '2020-05-08'), convert(date, '2020-11-14')),
             ('Ball', 'Red', convert(date, '2020-11-15'), convert(date, '9999-12-31')),
             ('Doll', 'Yellow', convert(date, '2020-01-01'), convert(date, '2020-03-24')),
             ('Doll', 'Green', convert(date, '2020-03-25'), convert(date, '2020-04-12')),
             ('Doll', 'Green', convert(date, '2020-04-13'), convert(date, '2020-05-07')),
             ('Doll', 'Green', convert(date, '2020-05-08'), convert(date, '2020-11-14')),
             ('Doll', 'Pink', convert(date, '2020-11-15'), convert(date, '9999-12-31')) 
) v(Item, Color, ValidFrom, ValidTo)
10 rows affected

select item, color, min(validfrom), max(validto)
from (select t.*,
             sum(case when prev_validto >= dateadd(day, -1, validfrom)
                      then 0 else 1
                 end) over (partition by item order by validfrom) as grp
      from (select t.*,
                   lag(validto) over (partition by item, color order by validfrom) as prev_validto
            from t
            ) t
     ) t
group by item, color, grp
order by item, min(validfrom)


item
color
(No column name)
(No column name)


Ball
Red
2020-01-01
2020-03-24

Ball
Blue
2020-03-25
2020-11-14

Ball
Red
2020-11-15
9999-12-31

Doll
Yellow
2020-01-01
2020-03-24

Doll
Green
2020-03-25
2020-11-14

Doll
Pink
2020-11-15
9999-12-31


select item, color, min(validfrom), max(validto)
from (select t.*,
             sum(case when tprev.color is null then 1 else 0
                 end) over (partition by t.item order by t.validfrom) as grp
      from t left join
           t tprev
           on tprev.item = t.item and
              tprev.color = t.color and
              tprev.validto = dateadd(day, -1, t.validfrom)
     ) t
group by item, color, grp
order by item, min(validfrom)


item
color
(No column name)
(No column name)


Ball
Red
2020-01-01
2020-03-24

Ball
Blue
2020-03-25
2020-11-14

Ball
Red
2020-11-15
9999-12-31

Doll
Yellow
2020-01-01
2020-03-24

Doll
Green
2020-03-25
2020-11-14

Doll
Pink
2020-11-15
9999-12-31

item	color	(No column name)	(No column name)
Ball	Red	2020-01-01	2020-03-24
Ball	Blue	2020-03-25	2020-11-14
Ball	Red	2020-11-15	9999-12-31
Doll	Yellow	2020-01-01	2020-03-24
Doll	Green	2020-03-25	2020-11-14
Doll	Pink	2020-11-15	9999-12-31