Hvordan kan jeg finde dublerede fortløbende værdier i denne tabel?

Brug lead- og laganalysefunktionerne.

create table t3 (d number, v number);
insert into t3(d, v) values(1, 1);
insert into t3(d, v) values(2, 2);
insert into t3(d, v) values(3, 2);
insert into t3(d, v) values(4, 3);
insert into t3(d, v) values(5, 2);
insert into t3(d, v) values(6, 3);
insert into t3(d, v) values(7, 4);

select d, v, case when v in (prev, next) then '*' end match, prev, next from (
  select
    d,
    v,
    lag(v, 1) over (order by d) prev,
    lead(v, 1) over (order by d) next
  from
    t3
)
order by
  d
;

Matchende naboer er markeret med * i matchkolonnen,