I'm trying to calculate the total purchase amount of each customer from the database available online on W3 Schools
The tables I'm using are:
Customers
Orders
Products
OrderDetails
My current query gives me the product wise purchase amount for the customer. What I need is the total purchase amount.
SELECT c.CustomerID,o.OrderID,(ord.Quantity*p.Price) as
Total_Amount
from Customers c inner join Orders o
inner join Products p
inner join OrderDetails ord
on c.CustomerID = o.CustomerID
and o.OrderID = ord.OrderID
and ord.ProductID = p.ProductID;
My Output:
I need the sum for the values with the same order id and customer id.
I tried out group-by and sum but it gives me the overall sum of all the products.
You simply want a GROUP BY:
SELECT c.CustomerID, SUM(ord.Quantity*p.Price) as
Total_Amount
FROM Customers c inner join Orders o
on c.CustomerID = o.CustomerID join
OrderDetails ord
on o.OrderID = ord.OrderID join
Products p
on ord.ProductID = p.ProductID
GROUP BY CustomerID;
Note that this orders the JOINs so the ON clauses are interleaved. This is how JOINs are normally written.
If you need the sum for the values with the same order id and customer id, then you need to group the rows based on both customer id and order id.
SELECT c.CustomerID,o.OrderID,SUM(ord.Quantity*p.Price) as Total_Amount
from Customers c inner join Orders o
inner join Products p
inner join OrderDetails ord
on c.CustomerID = o.CustomerID
and o.OrderID = ord.OrderID
and ord.ProductID = p.ProductID
Group By c.CustomerID,o.OrderID
In this Database I want to count the number of orders that contain only products of a certain category.
I know how to count all orders that also contain items of a certain category, i.e. category 1:
SELECT Count(DISTINCT orderdetails.orderid) AS "AllCat1"
FROM orderdetails
INNER JOIN orders
ON orderdetails.orderid = orders.orderid
AND orderdetails.productid IN (SELECT DISTINCT productid
FROM products
WHERE categoryid = 1)
WHERE orderdate BETWEEN "1996-12-01" AND "1996-12-31";
I am having trouble finding an elegant way to get all orders that contain only category 1 items. I tried selecting all OrderIDs and grouping them by OrderID AND CategoryID:
SELECT *
FROM orderdetails
INNER JOIN orders
ON orderdetails.orderid = orders.orderid
AND orderdate BETWEEN "1996-12-01" AND "1996-12-31"
INNER JOIN products
ON orderdetails.productid = products.productid
GROUP BY orderdetails.orderid,
categoryid;
But I have no idea how to count all OrderIDs that contain category 1 items exclusively. Is my approach right? Or is there a better way to do it (Which I am sure there is)
You can use group by and having . . . but you need two levels. To get the orders that are all in one (or a set of categories) by doing:
SELECT o.orderId
FROM orders o JOIN
orderdetails od
ON od.orderid = o.orderid JOIN
products p
ON p.productid = od.productid
WHERE o.orderdate BETWEEN '1996-12-01' AND '1996-12-31'
GROUP BY o.orderId
HAVING SUM(CASE WHEN p.categoryid IN (1) THEN 1 ELSE 0 END) = COUNT(*);
The count needs a subquery:
SELECT COUNT(*)
FROM (SELECT o.orderId
FROM orders o JOIN
orderdetails od
ON od.orderid = o.orderid JOIN
products p
ON p.productid = od.productid
WHERE o.orderdate BETWEEN '1996-12-01' AND '1996-12-31'
GROUP BY o.orderId
HAVING SUM(CASE WHEN p.categoryid IN (1) THEN 1 ELSE 0 END) = COUNT(*)
) o;
You can do filtering using HAVING clause. We basically Count the order details rows where category is 1 for an order. It should be equal to the total count of rows for that order. This would ensure that all the categories in an order is 1 only.
SELECT od.orderid
FROM orderdetails AS od
INNER JOIN orders AS o
ON od.orderid = o.orderid
AND o.orderdate BETWEEN "1996-12-01" AND "1996-12-31"
INNER JOIN products AS p
ON od.productid = p.productid
GROUP BY od.orderid
HAVING COUNT(CASE WHEN p.categoryid = 1 THEN 1 END) = COUNT(*)
It is advisable to use Aliasing in case of multi-table queries for Code clarity and readability
I am trying to show the average price of products bought by customers from ‘Tucson’, however this query returns null even though there are two customers that have placed orders from Tuscon.
select AVG(product_price) from product where product_id in
(select product_id from orderline where order_id in
(select order_id from ordertable where cust_id in
(Select cust_id from customer where city = 'Tuscon')))
You're using fom instead of from in your query: select order_id fom ordertable where cust_id in
This should be select order_id from ordertable where cust_id in
fom is not a recognized keyword. The MySQL parser doesn't know what to do with that, so it throws an error about "invalid syntax".
Consider using join operations in place of nested IN subqueries. If we are guaranteed:
product_id is unique in product table
order_id is unique in ordertable table
cust_id is unique in customer table
then we can get an equivalent result set, the average of the price of distinct products that were ordered...
SELECT AVG(p.product_price)
FROM ( SELECT l.product_id
FROM orderline l
JOIN ordertable o
ON o.order_id = l.order_id
JOIN customer c
ON c.cust_id = o.cust_id
WHERE c.city = 'Tuscon'
GROUP BY l.product_id
) q
JOIN product p
ON p.product_id = l.product_id
If we want that "average price" of all products ordered (a different result, with the average taking into account the number of times a product was ordered...then we could use a query like this:
SELECT AVG(p.product_price)
FROM product p
JOIN orderline l
ON l.product_id = p.product_id
JOIN ordertable o
ON o.order_id = l.order_id
JOIN customer c
ON c.cust_id = o.cust_id
WHERE c.city = 'Tuscon'
I need to find the first and last name of the customer who has purchased the most expensive product.
Schema
Orders
orderID
ordertypeID
customerID
quantity
purchasedate
Customers
customerID
state
postcode
streetNumber
streetAddress
customerLn
customerFn
Order_Contents
orderID
productID
quantity
Products
productID
productCategory
productName
productDescription
unitPrice
inStock
How can i write this query?
You can use sub queries as follows.
select
Customers.customerFN,
Customers.customerLN
from
Customers
inner join Orders on Orders.customerID = Customers.customerID
inner join Order_Contents on Order_Contents.orderID = Orders.orderID
where
Order_Contents.productID in
(select Products.productID from Products where Products.unitPrice = (select max(Products.unitPrice) from Products))
Something like this seems like it should work as a jumping off point (completely naive approach here)
SELECT CustomerFn, CustomerLn FROM Customers c
LEFT JOIN Orders o on o.customerID = c.customerID
LEFT JOIN Order_Contents oc on oc.orderID = o.orderID
LEFT JOIN Products p on p.productID = oc.productID
WHERE oc.productID IN (
SELECT productID FROM Products WHERE unitPrice = MAX(unitPrice)
);
select c.customerFn, c.customerLn
from customers c join orders o where o.customerID = c.customerID
join order_contents l where l.orderId = o.orderId
join products p where p.productId = l.productId
order by p.unitPrice desc
limit 1
I am new to database field. I am currently learning mysql using Murach's Mysql. I came across following problem in the book but I am not able to figure out the correct query for solving it.
Write a SELECT statement that
joins the
Customers, Orders, Order_Items, and
Products tables. This statement should return these columns:
last_name,
first_name,
order_date, product_na
me, item_price, discount_amount,
and
quantity
.
Use aliases for the tables.
Sort the final result set by
last
_name,
order
_date, and
product_name
.
By far I have this query:
select last_name , first_name , order_date , product_name , tem_price,
discount_amount, quantity
from customers , orders , order_items product
order by last_name , order_date , product_name
You can use inner join for these 4 tables Customers , Orders, Order_items , Products but make sure there is a match between the columns in these 3 tables.
Example of the sql query based on the given information. (Assume CustomerID is a match between the columns)
Select A.last_name,A.first_name,B.order_date,B.product_name,C.item_price,C.discount_amount,D.quantity
from TB_Customers A inner join TB_Orders B on A.CustomerID = B.CustomerID
inner join TB_Order_Items C on B.CustomerID = C.CustomerID on
inner join TB_Products D on C.CustomerID = D.CustomerID Where D.CustomerID ='TEST111'
Using ANSI standard join syntax:
SELECT c.last_name, c.first_name, o.order_date, p.product_name,
p.item_price, p.discount_amount, p.quantity
FROM Customers AS c
INNER JOIN Orders AS o ON c.order_id = o.order_id
INNER JOIN Order_Items AS i ON o.order_id = i.order_id
INNER JOIN Products AS p ON i.product_id = p.product_id
ORDER BY c.last _name, o.order _date, p.product_name
Well, we are going to analize the query. Since you didn't specify the database structure, I'm going to do an aproaching.
"SELECT statement that joins the Customers, Orders, Order_Items, and Products tables."
This is refered to the tables, this is in the FROM clause. You have to join them with WHERE clause.
SELECT *
FROM Customers, Orders, Order_Items, Products
WHERE Customers.order_id = Orders.order_id
AND Order_Items.order_id = Orders.order_id
AND Products.product_id = Order_Items.product_id
"This statement should return these columns: last_name, first_name, order_date, product_na me, item_price, discount_amount, and quantity "
This part is refered to the SELECT clause.
SELECT last_name, first_name, order_date, product_name,
item_price, discount_amount, quantity
FROM Customers, Orders, Order_Items, Products
WHERE Customers.order_id = Orders.order_id
AND Order_Items.order_id = Orders.order_id
AND Products.product_id = Order_Items.product_id
"Use aliases for the tables"
This part involves the whole query and means that have to rename the tables (virtually and only form this query) and in every reference you have to use the new name.
SELECT c.last_name, c.first_name, o.order_date, p.product_name,
p.item_price, p.discount_amount, p.quantity
FROM Customers AS c, Orders AS o, Order_Items AS i, Products AS p
WHERE c.order_id = o.order_id
AND i.order_id = o.order_id
AND p.product_id = i.product_id
"Sort the final result set by last _name, order _date, and product_name."
This part refered to th ORDER BY clause. You have to keep in mind the aliases
SELECT c.last_name, c.first_name, o.order_date, p.product_name,
p.item_price, p.discount_amount, p.quantity
FROM Customers AS c, Orders AS o, Order_Items AS i, Products AS p
WHERE c.order_id = o.order_id
AND i.order_id = o.order_id
AND p.product_id = i.product_id
ORDER BY c.last _name, o.order _date, p.product_name