Your Query does not include the specified expression, how to fix it? - sql

Question

I don't understand why my sql is not running,
it pop out a window say
"Your query does not include the specified expression ' SUM(SaleRecord.Number)*(product.Price' as part of an aggregate function"
SELECT SUM(SaleRecord.Number)*(Product.Price) AS TotalIncome
FROM Product, SaleRecord
WHERE Product.ProductID=SaleRecord.SaleProduct;

Answer 1

Product.Price is not part of the aggregate. Presumably, you intend:
SELECT SUM(SaleRecord.Number * Product.Price) AS TotalIncome
FROM Product INNER JOIN
SaleRecord
ON Product.ProductID=SaleRecord.SaleProduct;
Note that I also fixed the archaic join syntax.

Answer 2

You asked in my previous answer:
"thank you, I just make some mistake, now it is working. And sorry to
bother you more, I want to select the product who sell the most out,
how can I do it, I try to add MAX(xxx) on it, and it don't work"
Now, I am by no means an expert, but there are two processes going on. Your language is confusing so I'm going to assume you want to know which product sells the most in $$ terms (rather than count. For example, you might sell 1,000 $0.50 products, equallying $500 total sales, or 10 $500 products, totallying $5000. If you want the count or the dollar value, then the method changes slightly).
So the first process is to get the total sales of each product, which I outlined above. Then you want to nest that inside a second query, where you then select the max. I'll give you the code and then explain it:
SELECT ProductID, MAX(TotalSale)
FROM (
SELECT P.ProductID, SUM(S.Number)*P.Price AS TotalSale
FROM Products as P, SaleRecords as S
WHERE product.Productid = SaleRecord.SaleProduct
GROUP BY Product.ProductID
)
It's easiest to imagine this as querying a query. Your first query is in the FROM() statement. That will run and give you the output of total sale per product. Then the second query is ran (the top most SELECT line) that selects the productID and the sale amount that is the largest among all the products.
Your teacher may not like this since nesting queries is a little advanced (though completely intuitive IMO). Hopefully this helps!

Answer 3

You brackets are wrong - for each row you want to multiply the price by the number, and only then sum them:
SELECT SUM(SaleRecord.Number * Product.Price) AS TotalIncome
FROM Product, SaleRecord
WHERE Product.ProductID = SaleRecord.SaleProduct;

Answer 4

You have a bracket error:
SELECT SUM(SaleRecord.Number * Product.Price) AS TotalIncome
FROM Product INNER JOIN
SaleRecord ON Product.ProductID = SaleRecord.SaleProduct;

Answer 5

This is because you're not indicating which column to group by. The line you wrote is:
SUM(SaleRecord.Number) * Product.Price
Which sums all of the sale quantities (regardless of differences in product ID) and multiplies it by the price right? Well what if you have multiple products with different prices? Basically, you are doing a one to many match, where you have a total that is the sum of all the sales, multiplied by multiple prices. What you need is a group by command. I would modify your code to say:
SELECT Product.ProductID, SUM(SaleRecord.Number)*Product.Price AS TotalSales
FROM Product, SaleRecord
WHERE product.Productid = SaleRecord.SaleProduct
GROUP BY Product.ProductID
That should take care of it, telling the dbms to group each product together, sum the number of sales and then multiply by the price of that product.
You can nest that inside another query to get total Income:
SELECT SUM(TotalIncome)
FROM ( **the above code here)
EDIT: Or you can do it like the ways listed above where your query creates a TotalIncome for each ORDER, and then sums them all together. my way creates a total sale for each PRODUCT and then sums all the products