To delete similar rows.

Question

Hi.
I have table which contain amounts by accounts by periods of time. For example:
account_id | amount | date_from | date_until
1 | 100 | 01.01.2012| 01.01.2012
1 | 100 | 02.01.2012| 03.01.2012
1 | 100 | 04.01.2012| 04.01.2012
1 | 130 | 05.01.2012| 09.01.2012
1 | 100 | 10.01.2012| 30.01.2012
I want to delete repeated rows to get result like:
account_id | amount | date_from | date_until
1 | 100 | 01.01.2012| 04.01.2012
1 | 130 | 05.01.2012| 09.01.2012
1 | 100 | 10.01.2012| 30.01.2012
...and store them in another table.
I made script with analytic function:
select distinct account_id,
       amount,
       first_value (date_from) over (partition account_id, amount order by date_from) as date_from,
       last_value (date_until) over (partition account_id, amount order by date_from) as date_from
from balances .... but I get next:
account_id | amount | date_from | date_until
1 | 100 | 01.01.2012| 30.01.2012
1 | 130 | 05.01.2012| 09.01.2012
I have thought, "order" in analytic function must fix issues when records look the same, because partition key changes.

Answer 1

Hi Paul,
In below select I try to show you the steps I toke to get the result you want.
WITH
  a AS
    SELECT
      1 account_id
    , 100 amount
    , to_date('01.01.2012','dd.mm.yyyy') date_from
    , to_date('01.01.2012','dd.mm.yyyy') date_until
    FROM
      dual
    UNION ALL
    SELECT
      1 account_id
    , 100 amount
    , to_date('02.01.2012','dd.mm.yyyy') date_from
    , to_date('03.01.2012','dd.mm.yyyy') date_until
    FROM
      dual
    UNION ALL
    SELECT
      1 account_id
    , 100 amount
    , to_date('04.01.2012','dd.mm.yyyy') date_from
    , to_date('04.01.2012','dd.mm.yyyy') date_until
    FROM
      dual
    UNION ALL
    SELECT
      1 account_id
    , 130 amount
    , to_date('05.01.2012','dd.mm.yyyy') date_from
    , to_date('09.01.2012','dd.mm.yyyy') date_until
    FROM
      dual
    UNION ALL
    SELECT
      1 account_id
    , 100 amount
    , to_date('10.01.2012','dd.mm.yyyy') date_from
    , to_date('30.01.2012','dd.mm.yyyy') date_until
    FROM
      dual
,b AS
    SELECT
      account_id
    , amount
    , date_from
    ,date_until
    ,row_number() over (order by account_id, date_from) rn
    ,CASE
        WHEN amount = lag(amount, 1) over (order by account_id, date_from)
        THEN 0
        ELSE 1
      END AS start_group
    FROM
      a
,c AS
    SELECT
      b.*
    ,CASE
        WHEN start_group = 0
        THEN rn - row_number() over (partition BY account_id, amount order by rn) +1
        ELSE rn
      END grn
    FROM
      b
,d AS
    SELECT
      account_id
    ,amount
    ,MIN(date_from) date_from
    ,MAX(date_until) date_until
    FROM
      c
    GROUP BY
      account_id
    ,amount
    ,grn
SELECT * FROM d ORDER BY account_id ,date_from ;The rusult :
ACCOUNT_ID             AMOUNT                 DATE_FROM                 DATE_UNTIL               
1                      100                    01.01.2012                04.01.2012               
1                      130                    05.01.2012                09.01.2012               
1                      100                    10.01.2012                30.01.2012                Regards,
Peter