I'm learning SQL and I would like to know why I'm getting 'Error 1: could not prepare statement (1 no such column: avg_quantity)' when I try the following query on the
w3schools
WITH avg_quantity AS (SELECT AVG(OrderDetails.Quantity)
FROM OrderDetails)
SELECT Products.ProductName, OrderDetails.Quantity
FROM OrderDetails
JOIN Products ON Products.ProductID = OrderDetails.ProductID
WHERE OrderDetails.Quantity > avg_quantity
But when I try this code here, everything works fine:
SELECT Products.ProductName, OrderDetails.Quantity
FROM OrderDetails
JOIN Products ON Products.ProductID = OrderDetails.ProductID
WHERE OrderDetails.Quantity > (SELECT AVG(OrderDetails.Quantity)
FROM OrderDetails)
You still need a select against the CTE:
WITH cte AS (
SELECT AVG(Quantity) AS avg_quantity
FROM OrderDetails
)
SELECT p.ProductName, od.Quantity
FROM OrderDetails od
INNER JOIN Products p ON p.ProductID = od.ProductID
WHERE od.Quantity > (SELECT avg_quantity FROM cte);
Functionally speaking, a CTE behaves like inlined SQL code. It is not something like a user defined variable which stores some value (although on some RDBMS, CTEs can be materialized).
You can do just like Tim said.
Another solution would be to just add the new table (avg_quantity) to the query, for exemple on FROM like so:
WITH avg_quantity AS
(
SELECT AVG(OrderDetails.Quantity) AS avg
FROM OrderDetails
)
SELECT Products.ProductName, OrderDetails.Quantity
FROM OrderDetails, avg_quantity
JOIN Products ON Products.ProductID = OrderDetails.ProductID
WHERE OrderDetails.Quantity > avg_quantity.avg
Related
I searched and found similar questions online but not my particular one, they all use where or having clause.If theres one similar to mine please link it. It's a 2 part question and I have the first one done. Thank you in advance.
Okay so heres the question, part 1
"Find by customer, the total cost and the total discounted cost for each product on the order ?".
It also asks to use inner joins to find the customer and order it a specific way. Below is the answer.
SELECT
C.companyname, O.orderid, O.orderdate, P.productname,
OD.orderid, OD.unitprice, OD.qty, OD.discount,
(OD.unitprice * OD.qty - (OD.qty * OD.discount)) AS TotalCost,
(OD.qty * OD.discount) AS TotalDiscountedCost
FROM
Sales.Customers AS C
INNER JOIN
Sales.Orders AS O ON C.custid = O.custid
INNER JOIN
Sales.OrderDetails OD ON O.orderid = OD.orderid
INNER JOIN
Production.Products as P ON OD.productid = P.productid
ORDER BY
C.companyname, O.orderdate;
Now the second question is to
follow up and resume the first one by "customer and the order date year, the total cost and the total discounted cost on the order ?". It also asks for this, "Project following columns in the select clause as.
GroupByColumns.companyname
GroupByColumns.OrderdateYear
AggregationColumns.CountNumberOfIndividualOrders
AggregationColumns.CountNumberOfProductsOrders
AggregationColumns.TotalCost
AggregationColumns.TotalDiscountedCost
Finally to order by company name and orderdateYear( which are groups). Where im stuck is how to count the specific orders of qty that equal 1 as an aggregate function in the SELECT clause. I know it has to use the aggregate function COUNT because of the GROUP BY, just don't know how to. This is what I have.
SELECT
C.companyname, YEAR(O.orderdate) AS orderyear,OD.qty,
-- Where in the count function or if theres another way do I count all the
--single orders
--COUNT(OD.qty) AS indiviualorders,
(OD.unitprice * OD.qty - (OD.qty * OD.discount)) AS TotalCost,
(OD.qty * OD.discount) AS TotalDiscountedCost
FROM
Sales.Customers AS C
INNER JOIN
Sales.Orders AS O ON C.custid = O.custid
INNER JOIN
Sales.OrderDetails OD ON O.orderid = OD.orderid
INNER JOIN
Production.Products as P ON OD.productid = P.productid
GROUP BY
C.companyname, YEAR(O.orderdate)
ORDER BY
C.companyname, O.orderdate;
You case use a case statement inside a sum
SUM(CASE WHEN <xyz> THEN 1 ELSE 0 END)
But for the count of unique orders, use SELECT(DISTINCT ) on a key that is unique in the order table
SELECT COUNT(DISTINCT O.OrderID) As DistinctOrders FROM Table
Guys so as part of my job as a Data Support Analyst I am training up to become a software developer, my mentor gave me a group of test statements and this one seems way more advanced than anything I have done previously. The question is...
*
6) Write a subquery or common table expression to calculate total
orders for each product category. that will Write a query that will
bring back each product name, the total number of orders made for the
product and join to the subquery or CTE to calculate the percentage
of sales that product represents of its product category. For example,
if Category of Soaps has 2 products; Blue Soup and Red Soap, blue soup
had 40 orders and red soaps had 10 orders I would expect to see the
following rows: Product Name Total Orders % of Category Red
Soap 40 80%
Blue Soap 10 20%
*
So far I have managed to get the following but I'm struggling to progress past this...
;WITH [Products] (CategoryId, TotalNumberOfOrders)
AS (
SELECT p.CategoryId,
COUNT (OD.OrderID) as TotalNumberOfOrders
FROM [dbo].[Products] p
INNER JOIN [dbo].[Order Details] OD
ON p.ProductID=OD.ProductID
GROUP BY p.CategoryId )
SELECT * From Products
Any help would be fantastic! ( I'm using NORTHWND database btw)
I think what you need is
;WITH temp AS
(
SELECT p.CategoryId,
COUNT (DISTINCT OD.OrderID) as TotalNumberOfOrders
FROM [dbo].[Products] p
INNER JOIN [dbo].[Order Details] OD ON p.ProductID=OD.ProductID
GROUP BY p.CategoryId
)
SELECT p.ProductName,
Count(DISTINCT Od.OrderId) AS Total,
Count(DISTINCT Od.OrderId)*100/temp.TotalNumberOfOrders AS Percentage
FROM Products p
INNER JOIN [dbo].[Order Details] OD ON p.ProductId = OD.ProductId
INNER JOIN temp ON p.CategoryId = temp.CategoryId
GROUP BY p.ProductId, p.ProductName, temp.TotalNumberOfOrders
Remember Count(Distinct..) to count Order.
Using a sub-Query:
SELECT P.ProductName,
COUNT(OrderID) AS NumberOfOrders,
CAST((CAST(COUNT(OrderID) AS DECIMAL(9,2)) / CAST(Derived_Table.CNT AS
DECIMAL(9,2))) * 100 AS DECIMAL(9,2)) AS Percentage
FROM [Northwind].[dbo].[Order Details]
INNER JOIN dbo.Products AS P
ON [Order Details].ProductID = P.ProductID
INNER JOIN (SELECT COUNT(F.OrderID) AS CNT, P.CategoryID
FROM [Northwind].[dbo].[Order Details] F
INNER JOIN dbo.Products P
ON F.ProductID = P.ProductID
GROUP BY P.CategoryID) AS Derived_Table
ON P.CategoryID = Derived_Table.CategoryID
GROUP BY [Order Details].ProductID, P.ProductName, Derived_Table.CNT
ORDER BY [Order Details].ProductID
Task: Select all orders having products belonging to ‘Sea Food’ category.
Result: OrderNo, OrderDate, Product Name
I write this query but it returns Cartesian products.
select o.orderid, o.orderdate as "Order Date", p.productname , ct.categoryname from orders o,
order_details od , products p , customers c ,categories ct
where
od.orderid = o.orderid and p.productid = od.productid and ct.categoryid = p.categoryid
and ct.categoryname = 'Seafood';
Question: What is wrong with my query ?
You're doing a CROSS JOIN on customers table since you forgot to specify the connection. This is why you should use explicit JOIN syntax rather than old syntax using commas in WHERE clause.
After translating your query into explicit syntax, you will see that there is no WHERE condition involving customers table:
select
o.orderid,
o.orderdate as "Order Date",
p.productname,
ct.categoryname
from
orders o,
inner join order_details od on od.orderid = o.orderid
inner join products p on p.productid = od.productid
inner join categories ct on ct.categoryid = p.categoryid
cross join customers c -- either you don't need this table, or you need to specify conditions
where
ct.categoryname = 'Seafood'
Basically the reason you got it was that your where clause omitted join condition involving customers table, so you were left with:
from (...), customers -- cross join when joining condition not applied in where clause
I should have asked multiple questions in my other post. Thanks to all who have helped, I am now stuck on another one..
Using the w3schools db, List SupplierID, SupplierName and ItemSupplied (count of number of items supplied by a supplier), sort the list first by number of items supplied (descending) and then by supplier name (ascending)
SELECT supplierid,
suppliername,
p.productname,
Count(s.supplierid) AS itemssupplied
FROM [Suppliers] AS s
INNER JOIN [Products] AS p
ON p.supplierid = s.supplierid
GROUP BY p.productid,
p.productname
ORDER BY Count (p.productid, p.productname) DESC
order BY s.suppliername
It's giving me an error, then again I am ordering by multiple ones. I think there's something I am not quite understanding here.
My other question is
List customers for each category and the total of order placed by that customer in a given category. In the query show three columnm: CategoryName, CustomerName, and TotalOrders (which is price * quantity for orders for a given customer in a given category). Sort this data in descending order by TotalOrders.
SELECT cg.CategoryName,
c.CustomerName,
Sum(p.Price * od.Quantity) AS TotalOrders
FROM [products] AS p
INNER JOIN [orderdetails] AS od
ON od.ProductID = p.ProductID
INNER JOIN [orders] AS o
ON o.OrderID = od.OrderID
INNER JOIN [customers] AS c
ON c.customerID = o.CustomerID
INNER JOIN [categories] AS cg
ON cg.CategoryID = p.CategoryID
GROUP BY c.CustomerName
ORDER BY TotalOrders DESC
Can someone please check if my query is correct? Thank you once again!
Question 1
You are really close but you only need to state ORDER BY once (also make sure to include all shown fields in your GROUP BY unless you are aggregating them):
SELECT SupplierID, SupplierName, p.ProductName, count(s.SupplierID) AS ItemsSupplied
FROM [Suppliers] AS s
INNER JOIN [Products] AS p ON p.SupplierID = s.SupplierID
GROUP BY p.ProductID, p.ProductName, SupplierID, SupplierName -- Added SupplierID, SupplierName
ORDER BY COUNT (p.productID, p.ProductName) DESC, s.SupplierName
Notice that you just place multiple sorts on the same line with a comma separating them.
Question 2
You're almost there but you need to group by any field that is not being aggregated. So in order not to get a parsing error, I added the cg.CategoryName to the GROUP BY line.
SELECT cg.CategoryName, c.CustomerName, Sum(p.Price*od.Quantity) AS TotalOrders
FROM [Products] AS p
INNER JOIN [OrderDetails] AS od ON od.ProductID = p.ProductID
INNER JOIN [Orders] AS o ON o.OrderID = od.OrderID
INNER JOIN [Customers] AS c ON c.customerID = o.CustomerID
INNER JOIN [Categories] AS cg ON cg.CategoryID = p.CategoryID
GROUP BY c.CustomerName, cg.CategoryName --Added CategoryName
ORDER BY TotalOrders DESC
You have several problems with the first query:
You're grouping by ProductID and ProductName even though you want the number of items supplied by a supplier, which means that you want to group by SupplierID and SupplierName.
You're supplying too many arguments to the COUNT function, which takes a single column name or *.
You've included a ProductName column in your results, which is not called for.
You need to ORDER BY both the number of products supplied and the SupplierName.
With those points in mind:
SELECT
s.SupplierID,
s.SupplierName,
COUNT(p.ProductID) AS ItemsSupplied
FROM
[Suppliers] AS s
INNER JOIN [Products] AS p ON p.SupplierID = s.SupplierID
GROUP BY
s.SupplierID, s.SupplierName
ORDER BY
ItemsSupplied DESC,
s.SupplierName ASC
Your second query is quite close, you're just missing one point, which is that you're looking for total of order placed by that customer in a given category. This means that in addition to grouping by c.CustomerName, you need to group by cg.CategoryID:
SELECT
cg.CategoryName,
c.CustomerName,
SUM(p.Price*od.Quantity) AS TotalOrders
FROM
[Products] AS p
INNER JOIN [OrderDetails] AS od ON od.ProductID = p.ProductID
INNER JOIN [Orders] AS o ON o.OrderID = od.OrderID
INNER JOIN [Customers] AS c ON c.customerID = o.CustomerID
INNER JOIN [Categories] AS cg ON cg.CategoryID = p.CategoryID
GROUP BY
c.CustomerName, cg.CategoryID
ORDER BY
TotalOrders DESC
The first one has two order by clauses
ORDER BY COUNT (p.productID, p.ProductName) DESC
and
ORDER BY s.SupplierName
also some databases will complain when order by columns for queries using group by are not included in the selected columns
How do i use DISTINCT command in a SQL query to show the supplier id, company name, and the number of distinct products from that supplier that were ordered prior to a specific date? I ran the code in Access but it doesn't translate over to SQL efficiently. The table appears.
[Supplier ID Company Name Product Name Order Date
1 Exotic Liquids Chang 17-Aug-94
1 Exotic Liquids Chang 22-Nov-94
1 Exotic Liquids Aniseed Syrup 26-Sep-94]
The code I have so far is the following. Where I get confused is where to put the DISTINCT statement. Should it be immediately after the Select? Should it go in Parentheses in addition to the SELECT? Excuse my lack of knowledge on this subject in advance.
SELECT Suppliers.SupplierID, Customers.CompanyName, Products.ProductName,
Orders.OrderDate
FROM Suppliers INNER JOIN
Products ON Suppliers.SupplierID = Products.SupplierID CROSS JOIN
Customers INNER JOIN
Orders ON Customers.CustomerID = Orders.CustomerID
WHERE Orders.OrderDate <='1/1/1999'
ORDER BY Suppliers.SupplierID
You can either distinct by all columns selected :
SELECT DISTINCT
Suppliers.SupplierID, Customers.CompanyName, Products.ProductName,
Orders.OrderDate
FROM
Suppliers INNER JOIN
Products ON Suppliers.SupplierID = Products.SupplierID CROSS JOIN
Customers INNER JOIN
Orders ON Customers.CustomerID = Orders.CustomerID
WHERE
Orders.OrderDate <='1/1/1999'
ORDER BY
Suppliers.SupplierID
or use group by instead if you need to distinct only by SupplierID. DISTINCT is not a function, hence DISTINCT(Suppliers.SupplierID) means the same as simply put DISTINCT word after SELECT in this case (see the 2nd reference below).
For Reference :
http://blog.sqlauthority.com/2007/12/20/sql-server-distinct-keyword-usage-and-common-discussion/
http://weblogs.sqlteam.com/jeffs/archive/2007/10/12/sql-distinct-group-by.aspx
I'm pretty sure it's this:
SELECT DISTINCT(Suppliers.SupplierID), Customers.CompanyName, Products.ProductName,Orders.OrderDate
FROM Suppliers INNER JOIN
Products ON Suppliers.SupplierID = Products.SupplierID CROSS JOIN
Customers INNER JOIN
Orders ON Customers.CustomerID = Orders.CustomerID
WHERE Orders.OrderDate <='1/1/1999'
ORDER BY Suppliers.SupplierID