How to update this? please

Question

Dear all expert
I have 2 tables 'CUST_AND_MKT' and 'CUST_SUMMARY' as below
select * from cust_and_mkt;cust_id   mkt_id    sale_volume
C0001     M0124     10,000
C0001     M7208     4,000
C0001     M0010     1,000
C0444     M0080     340,000
C0444     M1200     100,000
C0878     M0505     450,000
select * from cust_summary;cust_id    cust_name         mkt_id   total_volume
C0001      JOHN EDWARD       <null>   15,000
C0444      SARAH LANE        <null>   440,000
C0878      TOMMY E.CLEK      <null>   450,000I want to assign marketing who has a maximun sale_volume
in each customer to take care customer. My problem is how
to write SQL command to update mkt_id from 'CUST_AND_MKT'
to 'CUST_SUMMARY' as below
cust_id    cust_name         mkt_id   total_volume
C0001      JOHN EDWARD       M0124    15,000
C0444      SARAH LANE        M0080    440,000
C0878      TOMMY E.CLEK      M0505    450,000Thank you all for your kindness
JOE-Thailand

Answer 1

SQL> select * from v$version;
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - 64bi
PL/SQL Release 10.2.0.2.0 - Production
CORE    10.2.0.2.0      Production
TNS for HPUX: Version 10.2.0.2.0 - Production
NLSRTL Version 10.2.0.2.0 - Production
SQL> create table cust_summary
  2  as
  3  with t
  4  as
  5  (select 'C0001' cust_id, 'JOHN EDWARD' cust_name, cast(null as varchar2(20)) mkt_id,
  6           15000 total_volume from dual union all
  7   select 'C0444', 'SARAH LANE', null, 440000 from dual union all
  8   select 'C0878', 'TOMMY E. CLEK', null, 450000 from dual
  9  )
10  select * from t;
Table created.
SQL> create table cust_and_mkt
  2  as
  3    with t
  4    as
  5  (select 'C0001' cust_id, 'M0124' mkt_id, 10000 sales_volume from dual union all
  6   select 'C0001', 'M7208', 4000 from dual union all
  7   select 'C0001', 'M0010', 1000 from dual union all
  8   select 'C0444', 'M0080', 340000 from dual union all
  9   select 'C0444', 'M1200', 100000 from dual union all
10   select 'C0878', 'M0505', 450000 from dual
11  )
12  select * from t;
Table created.
SQL> select * from cust_summary;
CUST_ CUST_NAME     MKT_ID               TOTAL_VOLUME
C0001 JOHN EDWARD                               15000
C0444 SARAH LANE                               440000
C0878 TOMMY E. CLEK                            450000
SQL> select * from cust_and_mkt;
CUST_ MKT_I SALES_VOLUME
C0001 M0124        10000
C0001 M7208         4000
C0001 M0010         1000
C0444 M0080       340000
C0444 M1200       100000
C0878 M0505       450000
6 rows selected.
SQL> l
  1      merge into cust_summary
  2      using (select cust_id, max(mkt_id) keep(dense_rank first order by sales_volume desc) mkt_id
  3             from cust_and_mkt
  4             group by cust_id
  5            ) cust_and_mkt
  6      on (cust_summary.cust_id = cust_and_mkt.cust_id)
  7      when matched
  8      then
  9*    update set mkt_id = cust_and_mkt.mkt_id
SQL> /
3 rows merged.
SQL> select * from cust_summary;
CUST_ CUST_NAME     MKT_ID               TOTAL_VOLUME
C0001 JOHN EDWARD   M0124                       15000
C0444 SARAH LANE    M0080                      440000
C0878 TOMMY E. CLEK M0505                      450000For more information check the following link.
Merge Oracle10g
http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/statements_9016.htm#SQLRF01606
Keep Analytics
http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/functions056.htm#SQLRF00641
Merge Oracle9i
http://download.oracle.com/docs/cd/B10501_01/server.920/a96540/statements_915a.htm#SQLRF01606
Hope that helps.
Regards
Raj
P.S : If you are using oracle 9i then when not matched is compulsory and you need to include that clause. For more information check the link on merge statement for Oracle 9i
[Edit : ] Added Oracle version and caveat for merge when using oracle 9i
Message was edited by:
R.Subramanian