Create a Monthly Report Procedure in ORACLE - oracle

Question

Ok this is a tricky one (for me at least) lets say I have the following tables--
TABLES
ORDERS
create table orders (
ono number(5) not null primary key,
cno number(5) references customers,
eno number(4) references employees,
received date,
shipped date);
ODETAILS
create table odetails (
ono number(5) not null references orders,
pno number(5) not null references parts,
qty integer check(qty > 0),
primary key (ono,pno));
PARTS
create table parts(
pno number(5) not null primary key,
pname varchar2(30),
qoh integer check(qoh >= 0),
price number(6,2) check(price >= 0.0),
olevel integer);
TABLES DATA
insert into orders values
(1020,1111,1000,'10-DEC-11','12-DEC-11');
insert into orders values
(1021,1111,1000,'12-JAN-12','15-JAN-12');
insert into orders values
(1022,2222,1001,'13-FEB-12','20-FEB-12');
insert into orders values
(1023,3333,1000,'12-MAR-12',null);
insert into odetails values
(1020,10506,1);
insert into odetails values
(1020,10507,1);
insert into odetails values
(1020,10508,2);
insert into odetails values
(1020,10509,3);
insert into odetails values
(1021,10601,4);
insert into odetails values
(1022,10601,1);
insert into odetails values
(1022,10701,1);
insert into odetails values
(1023,10800,1);
insert into odetails values
(1023,10900,1);
insert into parts values
(10506,'Land Before Time I',200,19.99,20);
insert into parts values
(10507,'Land Before Time II',156,19.99,20);
insert into parts values
(10508,'Land Before Time III',190,19.99,20);
insert into parts values
(10509,'Land Before Time IV',60,19.99,20);
insert into parts values
(10601,'Sleeping Beauty',300,24.99,20);
insert into parts values
(10701,'When Harry Met Sally',120,19.99,30);
insert into parts values
(10800,'Dirty Harry',140,14.99,30);
insert into parts values
(10900,'Dr. Zhivago',100,24.99,30);
Now I'm required to create a procedure which takes in a value as month and generates a report which contains the following--
a. Number of sales
b. Sales value
c. Most popular item
d. Least popular item
My approach
CREATE OR REPLACE PROCEDURE TEST_REPORT
(MONTH_NUMBER IN NUMBER )
AS
PARTS_NUMBER VARCHAR2(10);
SHIPPING_STATUS VARCHAR2(10);
V_ENO VARCHAR2(5);
V_PNO VARCHAR2(5);
SALES NUMBER(30);
V_MONTH VARCHAR2(10);
BEGIN
SELECT RECEIVED INTO V_MONTH FROM ORDERS WHERE
WHERE EXTRACT(MONTH FROM ORDERS.RECEIVED) = MONTH_NUMBER;
SELECT SUM(PRICE*QTY)
INTO SALES
FROM ORDERS,ODETAILS,PARTS
WHERE
EXTRACT(MONTH FROM ORDERS.RECEIVED) = MONTH_NUMBER
END TEST_REPORT;
Then bang my head explodes. I was thinking of using cursors.. but then I thought a SELECT query with different column alias would be simpler. But as it seems I cant get the syntax right and currently If I execute this procedure it gives me a an error
ORA-01422: exact fetch returns more than requested number of rows
As there is more than one record in the table. What approach would be right and logical? and also did I get the syntax right for the procedures? I would appreciate the help and guidance.
Many thanks
(P.S. I condemn the person's naming convention in the script which I had to run to create the tables)

Answer 1

Well, let's see:
Number of sales (I'm assuming "of each part"):
SELECT od.PNO, COUNT(*) AS SALE_COUNT
FROM ODETAILS od
INNER JOIN ORDERS o
ON od.ONO = o.ONO
WHERE EXTRACT(MONTH FROM o.RECEIVED) = &MONTH_NUMBER
GROUP BY od.PNO
Sales value:
SELECT od.PNO, p.PRICE, SUM(od.QTY) AS SALES_QTY, SUM(od.QTY * p.PRICE) AS SALES_VALUE
FROM ODETAILS od
INNER JOIN PARTS p
ON p.PNO = od.PNO
GROUP BY od.PNO, p.PRICE
Most popular item (just take the first row):
SELECT od.PNO, SUM(od.QTY) AS TOTAL_QTY
FROM ODETAILS od
GROUP BY od.PNO
ORDER BY SUM(od.QTY) DESC
Least popular item (which has any sales) (just take the first row):
SELECT od.PNO, SUM(od.QTY) AS TOTAL_QTY
FROM ODETAILS od
GROUP BY od.PNO
ORDER BY SUM(od.QTY) ASC
Number of order cancellations and value, number of returns and values, item that has highest return: there does not appear to be data in the question (at this point) which would supply this information. I'll add a comment to the question to this effect. If further information or explanations are forthcoming I'll include this in my answer.
Best of luck.

Answer 2

Both these queries have issues.
Below query will return more than one record from ORDERS table. INTO clause will work only when the query returns exactly one record at a time.
SELECT RECEIVED INTO V_MONTH FROM ORDERS WHERE
WHERE EXTRACT(MONTH FROM ORDERS.RECEIVED) = MONTH_NUMBER;
This query have 2 issues, no join between ORDERS, ODETAILS and PARTS as well as INTO clause. Here also it will return more than one record.
SELECT SUM(PRICE*QTY)
INTO SALES
FROM ORDERS,ODETAILS,PARTS
WHERE
EXTRACT(MONTH FROM ORDERS.RECEIVED) = MONTH_NUMBER
END TEST_REPORT;
You need to define your requirement to suggest approach for your application.