How to count consecutive duplicates in a table?

Question

I have below question:
Want to find the consecutive duplicates

SLNO   NAME     PG   
1       A1      NO                   
2       A2      YES                    


        

Answer 1

Just for completeness, here's the actual Tabibitosan method:

with sample_data as (select 1 slno, 'A1' name, 'NO' pg from dual union all 
                     select 2 slno, 'A2' name, 'YES' pg from dual union all
                     select 3 slno, 'A3' name, 'NO' pg from dual union all
                     select 4 slno, 'A4' name, 'YES' pg from dual union all
                     select 6 slno, 'A5' name, 'YES' pg from dual union all
                     select 7 slno, 'A6' name, 'YES' pg from dual union all
                     select 8 slno, 'A7' name, 'YES' pg from dual union all
                     select 9 slno, 'A8' name, 'YES' pg from dual union all
                     select 10 slno, 'A9' name, 'YES' pg from dual union all
                     select 11 slno, 'A10' name, 'NO' pg from dual union all
                     select 12 slno, 'A11' name, 'YES' pg from dual union all
                     select 13 slno, 'A12' name, 'NO' pg from dual union all
                     select 14 slno, 'A14' name, 'NO' pg from dual)
-- end of mimicking a table called "sample_data" containing your data; see SQL below:
select max(cnt) max_pg_in_queue
from   (select   count(*) cnt
        from     (select slno,
                         name,
                         pg,
                         row_number() over (order by slno)
                           - row_number() over (partition by pg
                                                order by slno) grp
                  from   sample_data)
        where    pg = 'YES'
        group by grp);

MAX_PG_IN_QUEUE
---------------
              6