Two cursors with interdependency: how to code ?

Question

Hi,
I'm a newbe to pl/sql.
I've two tables: customers and purchases. A customer can have more than on purchase. I want to create invoices, for each customer one invoice for all purchases in this year. (Simplified for this situation).
I created a cursor for customers, c_cust (select cust_id from customers).
Now I want to create a cursor for purchases for each customer in the other cursor.
But how to program in the loop of c_cust the loop for purchases of the customer in the c_cust?
Any reaction will be appreciated.
Leo

Answer 1

The fastest and easiest way is using a single insert statement.
Something like this:
SQL> create table customers (id, name)
  2  as
  3  select 1, 'customer 1' from dual union all
  4  select 2, 'customer 2' from dual union all
  5  select 3, 'customer 3' from dual
  6  /
Tabel is aangemaakt.
SQL> create table purchases (id, customer_id, purchase_date, amount)
  2  as
  3  select 1, 1, date '2006-11-11', 10 from dual union all
  4  select 2, 1, date '2007-01-01', 20 from dual union all
  5  select 3, 1, date '2007-02-02', 30 from dual union all
  6  select 4, 1, date '2007-03-03', 40 from dual union all
  7  select 5, 3, date '2007-04-04', 50 from dual union all
  8  select 6, 3, date '2007-05-05', 60 from dual union all
  9  select 7, 3, date '2007-06-06', 70 from dual
10  /
Tabel is aangemaakt.
SQL> create table invoices
  2  ( customer_id number(6)
  3  , year date
  4  , total_amount number(9,2)
  5  )
  6  /
Tabel is aangemaakt.
SQL> insert into invoices (customer_id,year,total_amount)
  2  select customer_id
  3       , date '2007-01-01'
  4       , nvl(sum(p.amount),0)
  5    from customers c
  6       , purchases p
  7   where c.id = p.customer_id (+)
  8     and p.purchase_date(+) between date '2007-01-01' and date '2008-01-01' - interval '1' second
  9   group by customer_id
10  /
3 rijen zijn aangemaakt.
SQL> select * from invoices
  2  /
CUSTOMER_ID YEAR                TOTAL_AMOUNT
          1 01-01-2007 00:00:00           90
          3 01-01-2007 00:00:00          180
            01-01-2007 00:00:00            0
3 rijen zijn geselecteerd.You may skip the outer join if you don't want to generate an invoice if a customer doesn't have a purchase in a year.
Groet,
Rob.