mysql - Joining two table with SUM of Column and Group by another column -

need join , group sum() function 2 tables.
the tables under:

 debit table                 credit table                 ---------------------       --------------------- customername    debit       customername    credit ---------------------       --------------------- customer1       200.00      customer1       100.00 customer1       300.00      customer1       100.00 customer2       100.00      customer1       100.00 customer2       600.00      customer2       200.00 -----------------------     customer2       300.00                             customer2       50.00                             ----------------------- 

i need show 2 join table as:

 join table(debit credit table)               ------------------------------------------ customername    debit   credit  closing ------------------------------------------ customer1       500.00  300.00  200.00 customer2       700.00  550.00  150.00 ------------------------------------------ 

this far getting doesn't yield right result:

  "select debit_tbl.customername, sum(debit_tbl.debit) debit, sum(credit_tbl.credit) credit, sum(debit_tbl.debit) - sum(credit_tbl.credit) closing debit_tbl left outer join credit_tbl on debit_tbl.customername = credit_tbl.customername group debit_tbl.debit union select debit_tbl.customername, sum(debit_tbl.debit) debit, sum(credit_tbl.credit) credit, sum(debit_tbl.debit) - sum(credit_tbl.credit) closing debit right outer join credit_tbl on debit_tbl.customername = credit_tbl.customername group debit_tbl.debit" ------------------------------------------- 

this should work:

select customername,   debit,   credit,   debit-credit closing   (select d.customername customername,     sum(d.debit)         debit,     sum(c.credit)        credit   debit d   inner join credit c   on d.customername = c.customername   )