Master Child tables how to get the latest rows from both

Question

Hi,
Need some help with the sql. I have two tables Master & Child. In my Master table I have multiple rows for the same record and in the child table also multiple rows for the same master row how can I get the latest one's from both.
For example Data in my Master table looks like
CONT_ID                  SEQ_NUM        DESCRIPTION
1                         189             Update 2
1                         188             Update 1
1                         187              NewNow in the child table for the same CONT_ID I may have the following rows
CONT_ID                   UPDATED_DATE                                     STATUS
1                        3/16/2010 2:19:01.552700 PM                          P
1                        3/16/2010 12:29:01.552700 PM                         A
1                        3/16/2010 12:29:01.552700 PM                         P
1                        3/16/2010 12:19:01.552700 PM                         NIn my final query how can I get the row with seq_num 189 as it's the latest in Master table and from child table the row with status of P as it's the latest one based on the time. Here is the query i have but it returns the latest row from the child table only and basically repeats the master table rows as opposed to one row that is latest from both:
Thanks

Answer 1

Hi,
You can use the analytic ROW_NUMKBER function to find the latest row for each cont_id in each table:
WITH     got_m_rnum     AS
     SELECT     cont_id,     seq_num,     description
     ,     ROW_NUMBER () OVER ( PARTITION BY  cont_id
                               ORDER BY          seq_num     DESC
                       ) AS m_rnum
     FROM    master_table
--     WHERE     ...     -- any filtering goes here
,     got_c_rnum     AS
     SELECT     cont_id, updated_date,     status
     ,     ROW_NUMBER () OVER ( PARTITION BY  cont_id
                               ORDER BY          updated_date     DESC
                       ) AS c_rnum
     FROM    child_table
--     WHERE     ...     -- any filtering goes here
SELECT     m.cont_id,     m.seq_num,     m.description
,     c.updated_date,     c.status
FROM     got_m_rnum     m
JOIN     got_c_rnum     c     ON     m.cont_id     = c.cont_id
                    AND     m.m_rnum     = c.c_rnum
                    AND     m.m_rnum     = 1
;If you'd like to post CREATE TABLE and INSERT statements for the sample data, then I could test this.
If there happens to be a tie for the latest row (say, there are only two rows in the child_table with a certain cont_id, and both have exactly the same updated_date), then this query will arbitrarily choose one of them as the latest.