Tabel A                            TableB                                  Table C

 w_no  su0                        w_no    su1                         w_no     su2

1         10                            1           100                               1     1000

2        20                              1           100                              1    1000

                                              2         200                              2     2000

                                             2         200                              2   2000

내가원하는값은                  w_no          su0        su1        su2

                                                 1               10        200      2000

                                                  2              20        400     4000

select   a.w_no,su1,sum(b.su2),sum(c,su3)   from TableA  a   

left join Table b on a.w_no=b.w_no
left join Table c on a.w_no=c.w_no
group by a.w_no

결과값이  중복합이 나오네요 

결과값은                         w_no          su0        su1        su2

                                                 1               10        400     4000

                                                  2              20        800     8000

두개 table  조인해서 합은 되는데  3개조인하니까   중복되네요  부탁드립니다.