Update required

Question

I have a table accounts and the data looks like:
accno     cname     startdate     enddate
1     Tom     01-jan-201     null
2     Tom     01-aug-2011 null
Based on date,automatically new account number will be generated for the same customer.
Manually I want to update the enddate of first account number with start date of another account number for the same customer .so that the first account number will be ineffective and only one account number will be active.
I need an update statement to do the above.
Help in this regard very much appreciable.

Answer 1

NOT TESTED! assuming inserts already done
merge into accounts acc
using (select rownum row_no,startdate - 1 end_date
         from accounts ac
        where cname = acc.cname
          and startdate != (select max(startdate)
                              from accounts
                             where cname = ac.cname
      ) old
   on (acc.rownum = old.row_no)
when matched then update
                     set acc.enddate = old.end_dateRegards
Etbin