Question

Database Systems - (Query) I have duplicate invoices and I need to combine the customer balances. How do I write the equation?

Answer 1

There is a code, which delete duplicate invoices and combine all clear invoices :

delete test_outer.*
from test as test_outer
where exists(
select *
from test as test_inner
where test_inner.invoice = test_outer.invoice
group by invoice
having count(*) > 1
and min(test_inner.id) <> test_outer.id
);