PL/SQL block to populate a table

[keerthi11]

Hello Everyone,

Need help writing pl/sql to insert into table.


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

[davey23uk]

well seeing as this is your homework - what have you come up with so far

[keerthi11]

here's what i'm doing

--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..10
Loop
Insert into customer(customer_id,customer_name)
values(i, dbms_random.string('U',5));
If mod(i, 10) = 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..10
Loop
Insert into cust_products
values(10-i,i,add_months('04-nov-09',i));
If mod(i, 10) = 0 then
Commit;
End if;
End loop;
End;

--update customer table as required

Begin
For i in 1..10
Loop
update customer
set recently_purchased = 'N' where (select date_purchased from cust_products where customer_id = i) > '02-Feb-2010' and customer_id =i;

End loop;
End;

i'm worried this doesn't look professional..any suggestions please..the logic is working though.

[PAVB]

Good job.
I would probably rework the update statement - I see no reason to execute update statement ten times; a single execution of update statement should solve it.