Counter in a Sql statement

Question

Hi,
Given a column payment_type, where payment type varies, I need to count each time when the value of the payment_type changes and display the total count in the end.
For example,
payment_typ is 1 1 2 2 2 2 2 3 3 3 3 3 4. Total count should be 3. I need to traverse the values, capture the change and increment the counter.
Any help is appreciated.
Thanks

Answer 1

Does this one do the job as well?:
SQL> WITH t AS
     (SELECT     CASE
                    WHEN LEVEL <= 2
                       THEN 1
                    WHEN LEVEL <= 7
                       THEN 2
                    WHEN LEVEL <= 12
                       THEN 3
                    ELSE 4
                 END AS val
            FROM dual
      CONNECT BY LEVEL <= 13)
SELECT t.*,
       LAG (val) OVER (PARTITION BY val ORDER BY NULL) l
  FROM t
UNION ALL
SELECT NULL,
       COUNT (*)
  FROM (SELECT t.*,
               LAG (val) OVER (PARTITION BY val ORDER BY NULL) l
          FROM t)
WHERE l IS NULL
       VAL          L
         1          
         1          1
         2          
         2          2
         2          2
         2          2
         2          2
         3          
         3          3
         3          3
         3          3
         3          3
         4          
                    4
14 rows selected.(Maybe you want to substract 1 from result).