sql cross table calculations - sql-server

Question

Hi i need to write a query that does multiple things, i made it so it can get the details of orders from within a certain time frame as well as for ages between 20 and 30, however i need to check if the orders product cost more then a set amount
however that data is in multiple tables
one table has the orderid the prodcode and quantity, while the other day has the prod information such as code and price, and im 3rd from another table
So i need to access the price of the product with the prodcode and quantity to do a cross table calculation and see if its above 100 and trying to do this with an and where command
so if i have 3 tables
Orderplaced table with oid odate custno paid
ordered table with oid itemid quant
items itemid itemname price
and i need to do a calcultion across those tabkes in my query
SELECT DISTINCT Orderplaced.OID, Orderplaced.odate, Orderplaced.custno, Orderplaced.paid
FROM Cust, Orderplaced, items, Ordered
WHERE Orderplaced.odate BETWEEN '01-JUL-14' AND '31-DEC-14'
AND Floor((sysdate-Cust.DOB) / 365.25) Between '20' AND '30'
AND Cust.SEX='M'
AND items.itemid=ordered.itemid
AND $sum(ordered.quan*item.PRICE) >100;
no matter what way i try to get the calculation to work it doesnt seem to work always returns the same result even on orders under 100 dollars
so any advice on this would be good as its for my studies but is troubling me a lot

Answer 1

I think this is what you want. (I not familiar with $sum, I've replaced it with SUM())
SELECT
Orderplaced.OID,
Orderplaced.odate,
Orderplaced.custno,
Orderplaced.paid,
sum(ordered.quan * item.PRICE)
FROM
Cust
JOIN Orderplaced ON Cust.CustNo = Orderplaced.custno
JOIN Ordered ON Ordered.Oid = Orderplaced.Oid
JOIN items ON items.itemid = ordered.itemid
WHERE
Orderplaced.odate BETWEEN date 2014-07-01 AND date 2014-12-31
AND Floor((sysdate-Cust.DOB) / 365.25) Between 20 AND 30
AND Cust.SEX = 'M'
GROUP BY
Orderplaced.OID,
Orderplaced.odate,
Orderplaced.custno,
Orderplaced.paid
HAVING
sum(ordered.quant * item.PRICE) > 100;

Answer 2

I think you want to try something like this...
SELECT DISTINCT Orderplaced.OID, Orderplaced.odate, Orderplaced.custno, Orderplaced.paid
FROM Cust
JOIN Orderplaced ON
Cust.<SOMEID> = OrderPlaces.<CustId>
AND Orderplaced.odate BETWEEN '01-JUL-14' AND '31-DEC-14'
WHERE Floor((sysdate-Cust.DOB) / 365.25) Between 20 AND 30
AND Cust.SEX='M'
AND (
SELECT SUM(Ordered.quan*Item.PRICE)
FROM Ordered
JOIN Item ON Item.ItemId = Ordered.ItemId
WHERE Ordered.<SomeId> = OrderPlaced.<SomeId>) > 100
Couple of pointers:
1. Floor returns a number... you are comparing it to a string
2. Typically, when referencing a table in a query, the table has to be joined on its primary keys, ie. In your query you're referencing Item and ordered, without joining any of those tables on any key columns.
Hope that helps