SQL Server 2017

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create table t (v int not null, d date not null);
insert into t (v,d) values ( 3   , '1/1/2019'),
  (3   , '1/2/2019'),
  (3   , '1/3/2019'),
  (4   , '1/4/2019'),
  (4   , '1/5/2019'),
  (3   , '1/6/2019'),
  (3   , '1/7/2019'),
  (3   , '1/8/2019'),
  (3   , '1/9/2019'),
  (2   , '1/10/2019'),
  (2   , '1/11/2019'),
  (3   , '1/12/2019'),
  (3   , '1/13/2019'),
  (3   , '1/14/2019');
14 rows affected

select v, min(d) as mind, max(d) as maxd
from (
select v, d
     , row_number() over (order by d) 
     - row_number() over (partition by v order by d) as grp
from t
) as tmp
group by v, grp
order by min(d);     


v
mind
maxd


3
2019-01-01
2019-01-03

4
2019-01-04
2019-01-05

3
2019-01-06
2019-01-09

2
2019-01-10
2019-01-11

3
2019-01-12
2019-01-14

v	mind	maxd
3	2019-01-01	2019-01-03
4	2019-01-04	2019-01-05
3	2019-01-06	2019-01-09
2	2019-01-10	2019-01-11
3	2019-01-12	2019-01-14