PL/SQL block to populate a table

Question

Hello Gurus,
Need help to write a pl/sql block as per below:
1. Write a PL/SQL block which will populate the RESULTS table as described below. Consider performance implications (specifically where would you commit the queries) as we are dealing with millions of records.
The PL/SQL will:
- insert into the RESULTS table each customer id, and the number of unique products purchased by that customer.
- update the recently_purchased column of the customer table to 'Y' (yes if they have purchased a product in the last 12 months) or 'N' (if they have not purchased a product in the last 12 months).
Listed below are the tables & definitions:
table: CUSTOMER
columns:
customer_id NUMBER,
customer_name VARCHAR2(100),
recently_purchased VARCHAR2(1) -- 'Y' or 'N'
table: CUST_PRODUCTS
columns:
product_id NUMBER,
customer_id NUMBER,
date_purchased DATE
table: RESULTS
columns: customer_id NUMBER, product_count NUMBER
Thanks a lot..

Answer 1

Hi Guys,
I've tried this to my best but I feel like something's definately wrong with my update statement.
Please help..
--create customer table
create table customer (
customer_id number(6),
customer_name varchar2(100),
recently_purchased varchar2(1));
-- describe to see if it is created as required
desc customer
--populate customer table with random values
Begin
For i in 1..20
Loop
Insert into customer(customer_id,customer_name,recently_purchased)
values(i, dbms_random.string('U',5),'N');
If mod(i, 100000) = 0 then
Commit;
End if;
End loop;
End;
--create cust_products table
create table cust_products
(product_id number (6),
customer_id number(6),
date_purchased date);
--describe to see if table is created as required
desc cust_products
--populate cust_products with custome_id 1 to 10 and dates
Begin
For i in 1..20
Loop
Insert into cust_products
values(dbms_random.value(555,999),i,add_months('04-Nov-08',i));
If mod(i, 100000) = 0 then
Commit;
End if;
End loop;
End;
select * from cust_products
--update customer table as required
Begin
For i in 1..10
Loop
update customer set recently_purchased = 'Y';
commit;
update customer C set recently_purchased = 'N' where exists (select date_purchased from cust_products P where C.customer_id = P.customer_id );
commit;
End loop;
End;
--Insert into results table
select customer_id,count(product_id)
from cust_products
group by customer_id
Edited by: user497841 on Feb 4, 2010 2:12 PM