How would I delete duplicate data from two tables in Oracle SQL Developer -

my first table has columns id, invdate , invnumber values:

(1, 01/10/13, 1) (2, 02/10/13, 2) (2, 02/10/13, 2) (3, 03/10/13, 3) (4, 04/10/13, 4) (4, 05/10/13, 4) 

my second table b has columns id, dateofbirth, lastname, firstname values:

(1, 19/06/1997, fox, migan) (2, 30/07/1993, todd, james) (2, 30/07/1993, todd, james) (3, 1/08/1994, xi, ji) (4, 2/07/1992, fared, bob) (4, 2/07/1992, fared, bob)  

how use delete () function delete duplicated rows in both tables? think should merge tables somehow delete duplicated rows not sure.

as results,

select *  

should give:

(1, 01/10/13, 1) (2, 02/10/13, 2) (3, 03/10/13, 3) (4, 04/10/13, 4)  select * b;  

should give:

(1, 19/06/1997, fox, migan) (2, 30/07/1993, todd, james) (3, 1/08/1994, xi, ji) (4, 2/07/1992, fared, bob) 

update (solution) :

delete rowid>(select min(rowid) b a.id= b.id);

can explain sql me?

below example "b" table

taken here http://www.dba-oracle.com/t_delete_duplicate_table_rows.htm

(you can similar "a" table also)

  delete    b  t1      t1.rowid >    ( select  t2.rowid  b t2                   t1.id = t2.id ,  t1.dateofbirth = t2.dateofbirth , t1.lastname = t2.lastname ,  t1.firstname  = t2.firstname         );