Counting consecutive numbers in a view

Question

Say I have the following data in a table:
ID YEAR
1 2004
1 2005
1 2006
1 2008
1 2009
2 1998
2 1999
2 2000
Is there anyway to return a 3rd row in a query which would return a 1 if the previous rows YEAR was 1 different, but a 0 if otherwise. So the data would look like this:
ID YEAR COUNT
1 2004 0
1 2005 1
1 2006 1
1 2008 0
1 2009 1
2 1998 0
2 1999 1
2 2000 1
2 2001 1
2 2002 1
2 2006 0
I am basically trying to find out if someones yearly membership was a renewal. Here's the data:
with t1 as (select 1 as ID,2004 as YEAR from dual union
select 1,2005 from dual union
select 1,2006 from dual union
select 1,2008 from dual union
select 1,2009 from dual union
select 2,1998 from dual union
select 2,1999 from dual union
select 2,2000 from dual union
select 2,2001 from dual union
select 2,2002 from dual union
select 2,2006 from dual)
select ID,
YEAR
from t1
order by id, year;
Thanks,
Andrew

Answer 1

Thanks for providing sample data and expected results!
I think this is what you want.
SQL> with t1 as (select 1 as ID,2004 as YEAR from dual un
  2  select 1,2005 from dual union
  3  select 1,2006 from dual union
  4  select 1,2008 from dual union
  5  select 1,2009 from dual union
  6  select 2,1998 from dual union
  7  select 2,1999 from dual union
  8  select 2,2000 from dual union
  9  select 2,2001 from dual union
10  select 2,2002 from dual union
11  select 2,2006 from dual)
12  SELECT  ID
13  ,       YEAR
14  ,       (CASE
15                  WHEN YEAR - LAG(YEAR) OVER (PARTITION BY ID ORDER BY YEAR) = 1
16                  THEN 1
17                  ELSE 0
18          END) AS RENEWAL
19  FROM    t1
20  ORDER BY ID
21  ,       YEAR
22  /
        ID       YEAR    RENEWAL
         1       2004          0
         1       2005          1
         1       2006          1
         1       2008          0
         1       2009          1
         2       1998          0
         2       1999          1
         2       2000          1
         2       2001          1
         2       2002          1
         2       2006          0
11 rows selected.