was wondering if you could help me out with a SQL problem.
Example of the tables, please ingore the lack of relationships its just an example.
http://postimg.org/image/5imvjgl0t/
Right so basically I want to get all the CustomerID's associated with a certain countrycode I can get that by doing a simple query on the customer table however I then need to find out how many forms the customer has submitted in the order table.
I then need to get the title of the warehouse (one warehouse per countrycode) and the number of customers associated with that warehouse who have submitted a form.
So in summary I need to get a list of customerID's from the Customer table and count how many time they show up in the Order table. sort them into the warehouse echo the warehouse title with the number of orders.
What's the easiest way to go about this?
P.S. please ignore any data type / relationship issues with the image above, it's just an example.
SELECT w.title, c.CustomerID, COUNT(o.form_id) as cnt
FROM warehouse w
JOIN customer c USING (countrycode)
JOIN `Order` o USING (CustomerID)
GROUP BY w.siteid, c.CustomerID
ORDER BY w.title ASC, c.CustomerID
edit
If you want to include customers without any orders, you need a LEFT JOIN on the customers table:
SELECT w.title, c.CustomerID, COUNT(o.form_id) as cnt
FROM warehouse w
JOIN customer c USING (countrycode)
LEFT JOIN `Order` o USING (CustomerID)
GROUP BY w.countrycode, c.CustomerID
ORDER BY w.title ASC, c.CustomerID
To filter for only one customer:
SELECT w.title, c.CustomerID, COUNT(o.form_id) as cnt
FROM warehouse w
JOIN customer c USING (countrycode)
LEFT JOIN `Order` o USING (CustomerID)
WHERE c.CustomerId = 2
GROUP BY w.countrycode, c.CustomerID
ORDER BY w.title ASC, c.CustomerID
Related
first sorry, i don't have fluid english.
I want select 3 rows in 3 different tables, two of them without Foreing Key/relation.
Need to select amount of customers in each store, and total amount of payments in these stores in one query.
Here are the tables:
Customers
Stores
Payments
I have tried these querys to get payments for each store and customers for each store, but don't know how can unify in one query:
Payments/store
SELECT count(a.payment_id) as alquileres, b.store_id
FROM customer b, payment a
WHERE a.customer_id = b.customer_id
GROUP BY b.store_id;
customers/store
SELECT count(customer_id), store_id
FROM customer
GROUP BY store_id;
But when I add count(customer_id) in unique query don't have same results.
You can use one query:
select c.store_id,
count(distinct c.customer_id) as num_customers,
count(p.payment_id) as num_payments
from customers c left join
payments p
on p.customer_id = c.customer_id
group by c.store_id;
I'm struggling with a question that said Which customer has rented the
most films?
I am doing this using the Seikila sample database in MySQL. I have something that joins my tables together and attempts to give me a count but I know its wrong just looking at the actual data in the rental table.
my code is as below
SELECT r.rental_id, cust.customer_id, count(*) as Total_Rentals
FROM rental as r
INNER JOIN customer AS cust on r.customer_id = cust.customer_id
GROUP BY cust.customer_id;
but it tells me for example customer 1 has rented 32 movies, which I know is wrong. what am I doing wrong?
since I was asked for clarification, the database I am using is:
https://dev.mysql.com/doc/sakila/en/
And I am trying to find which customer has rented the most films, I am not entirely sure what my script is actually returning.
Remove the column rental_id from the select list and sort the result by count(*) descending to return the top 1 row:
SELECT cust.customer_id, cust.name, count(*) as Total_Rentals
FROM rental as r
INNER JOIN customer AS cust on r.customer_id = cust.customer_id
GROUP BY cust.customer_id, cust.name
ORDER BY Total_Rentals DESC LIMIT 1
But if you only need the customer's id then there is no need for a join:
SELECT customer_id, count(*) as Total_Rentals
FROM rental
GROUP BY customer_id
ORDER BY Total_Rentals DESC LIMIT 1
You need to join customer and rental, group by customer id (without rental id) and count it:
SELECT cust.customer_id, count(*) as Total_Rentals
FROM rental as r
INNER JOIN customer AS cust on r.customer_id = cust.customer_id
GROUP BY cust.customer_id;
So this code should work. If it doesn't work, that probably means that you have duplicates or other nonconventional issues.
I have a pretty simple MySQL question. I have two tables, Customer and Orders. Customer table has fields (id, name) and Order has fields (id, customerID, and item).
I can find which customer bought product A and customers that bought product B with the following query in MySQL.
SELECT DISTINCT c.`id`, c.name, o.`item`, o.qty FROM `customer` as c
INNER JOIN order AS o ON (c.`Id` = o.`customerID`)
where o.`item` ="Product A"
Union
SELECT DISTINCT c.`id`, c.name, o.`item`, o.qty FROM `customer` as c
INNER JOIN order AS o ON (c.`Id` = o.`customerID`)
where o.`item` ="Product B"
How can find the difference and similarity in these two result sets?
1) I.e. Customers that bought only product A but did not by product B
2) I.e. Customers that bought both product A and B
Thank you for your assistance.
D
You can try using the LEFT OUTER JOIN to get the result.
I have two tables customers and orders, below is the structure.
Table - customers
id
customer_name
Table - orders
id
order_id
customer_id
customers table have customers records and orders table have orders placed by customers,
customer_id in orders table is linked to the id field of customers table.
Now one customer can have zero or one or more than one orders, i want to get the last order placed by customers only.
when i run the following query a simple invisible join, it returns all the orders by the customer
SELECT customers.customer_name,orders.order_id FROM orders,customers WHERE orders.customer_id=customers.id
I have also tried different JOIN statements but cannot get the last order by the customer, i want to get it in one SQL query for all customers.
Thank you in advance for your help.
In MySQL there is just few ways to make it work (that I now actually). The first one is sort your table as desc before the join:
SELECT c.customer_name, o.customer_id, o.order_id,o.id FROM customers c
INNER JOIN orders o
ON o.id = (SELECT id FROM orders WHERE customer_id = c.id ORDER BY id DESC LIMIT 1)
Using in real time is the only way to get it done, but if you need to make some join on not real time you can create a temporary table or a alias table sorting it to make your select, like this:
CREATE TABLE tmp_your_table AS
SELECT * FROM orders ORDER BY id DESC
So now you are able to make this join work:
SELECT c.customer_name, o.customer_id, o.order_id,o.id FROM customers c
INNER JOIN tmp_your_table o ON o.id = tmp_your_table.id
Try this query
SELECT
c.customer_name,
max(o.order_id)
FROM
customers c
INNER JOIN
orders o
ON
o.customer_id = c.id
GROUP BY
c.customer_name
You don't have any date field in the order table so assuming the latest order will be the one which has max(order_id).
Try this query
SELECT
c.customer_name,
o.order_id
FROM
customers c
INNER JOIN
orders o
ON
o.customer_id = c.id
ORDER BY
o.id desc
LIMIT 1;
This is a part of SQL coding project of database.
I need to design a single table to hold orders made by customers.
Assume that customers' details (e.g. names) are stored in another table.
Using the table that I designed for orders, and this assumed other table, write
a single SQL query that can give the number of orders for every customer, one line per customer.
The “Orders” table
Order_ID Order_NO Customer_ID
1 8088 3
2 9632 1
3 1272 4
4 6037 1
Assume that the customer names and other details (address, phone numbers, emails) are stored in the “Customers” table.
My SQL:
SELECT Customers.FirstName, Customers.FirstName, Orders.OrderNo
FROM Customers
FULL JOIN Orders
ON Customers.Customer_ID = Orders.Customer_ID
ORDER BY Customers.LastName
Are there something wring with it ?
Change the query to inner join
SELECT
Customers.FirstName
, Customers.FirstName
, Orders.OrderNo
FROM
Customers
INNER JOIN Orders ON Customers.Customer_ID = Orders.Customer_ID
ORDER BY
Customers.LastName
Query for Ordercount for customer
SELECT
Customers.LastName
, COUNT(Orders.Order_Id)
FROM
Customers
INNER JOIN Orders ON Customers.Customer_ID = Orders.Customer_ID
GROUP BY
Customers.LastName
ORDER BY
Customers.LastName
Full join
http://www.w3schools.com/sql/sql_join_full.asp
Inner join
http://www.w3schools.com/sql/sql_join_inner.asp
If you just want to COUNT the orders you can do this:
SELECT
Customers.FirstName,
(
SELECT
COUNT(*)
FROM
Orders
WHERE
Orders.Customer_ID=Customers.Customer_ID
) AS NbrOfOrders
FROM
Customers
References:
12.15.1. GROUP BY (Aggregate) Functions
Don't forget COUNT and GROUP BY.