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;
Related
I have the following three tables:
I have Following Query to Join Above 3 Tables
customer.customer_id,
customer.name,
SUM(sales.total),
sales.created_at,
SUM(sales_payments.amount)
FROM
sales INNER JOIN customer ON customer.customer_id = sales.customer_id
INNER JOIN sales_payments ON sales.customer_id = sales_payments.customer_id
WHERE sales.created_at ='2020-04-03'
GROUP By customer.name
Result for Above Query is given below
Sum of sales.total is double of the actual sum of sales.total column which has 2-row count, I need to have the actual SUM of that column, without doubling the SUM of those rows, Thank you, for your help in advance..
PROBLEM
The problem here is that there are consecutive inner joins and the number of rows getting fetched in the second inner join is not restricted. So, as we have not added a condition on sales_payment_id in the join between the sales and sales_payment tables, one row in sales table(for customer_id 2, in this case) would be mapped to 2 rows in the payment table. This causes the same values to be reconsidered.
In other words, the mapping for customer_id 2 between the 3 tables is 1:1:2 rather than 1:1:1.
SOLUTION
Solution 1 : As mentioned by Gordon, you could first aggregate the amount values of the sales_payments table and then aggregate the values in sales table.
Solution 2 : Alternatively (IMHO a better approach), you could add a foreign key between sales and sales_payment tables. For example, the sales_payment_id column of sales_payment table can be introduced in the sales table as well. This would facilitate the join between these tables and reduce additional overheads while querying data.
The query would then look like:
`SELECT c.customer_id,
c.name,
SUM(s.total),
s.created_at,
SUM(sp.amount)
FROM customer c
INNER JOIN sales s
ON c.customer_id = s.customer_id
INNER JOIN sales_payments sp
ON c.customer_id = sp.customer_id
AND s.sales_payments_id = sp.sales_payments_id
WHERE s.created_at ='2020-04-03'
GROUP BY c.customer_id,
c.name,
s.created_at ;`
Hope that helps!
You have multiple rows for sales_payments and sales per customer. You need to pre-aggregate to get the right value:
SELECT c.customer_id, c.name, s.created_at, s.total, sp.amount
FROM customer c JOIN
(SELECT s.customer_id, s.created_at, SUM(s.total) as total
FROM sales s
WHERE s.created_at ='2020-04-03'
GROUP BY s.customer_id, s.created_at
) s
ON c.customer_id = s.customer_id JOIN
(SELECT sp.customer_id, SUM(sp.amount) as amount
FROM sales_payments sp
GROUP BY sp.customer_id
) sp
ON s.customer_id = sp.customer_id
I have these two tables:
invoices (contains id field)
contracts (contains fk to invoice + 'code' field)
Let's say I have one record in the invoices table and two records in the contracts table. Both records in the contracts table point to the same invoice record.
Desire: I'd like to count the amount of invoices.
What I've got so far:
select
c.code, count(*)
from
invoices i
join
contracts c
on
c.invoice_id = i.id
group by
c.code
Although the count shows two instead of the desired 1. I understand that this is because of the join on the contract table, but not sure how to fix this.
Try with COUNT(DISTINCT i.id); it should count the different invoice id's in the resultset.
select
c.code, count(distinct i.id)
from
invoices i
join
contracts c
on
c.invoice_id = i.id
group by
c.code
You want the number of invoices?
select count(*)
from invoices i
You want invoices with contracts?
select count( distinct c.invoice_id)
from
contracts
Your code finds number of contracts per each invoice
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'm building a MySQL query but I can't seem to get it right.
I have four tables:
- customers
- orders
- sales_rates
- purchase_rates
There is a 1:n relation 'customernr' between customers and orders.
There is a 1:n relation 'ordernr' between orders and sales_rates.
There is a 1:n relation 'ordernr' between orders and purchase_rates.
What I would like to do is produce an output of all customers with their total purchase and sales amounts.
So far I have the following query.
SELECT c.customernr, c.customer_name, SUM(sr.sales_price) AS sales_price, SUM(pr.purchase_price) AS purchase_price
FROM orders o, customers c, sales_rates sr, purchase_rates pr
WHERE o.customernr = c.customernr
AND o.ordernr = sr.ordernr
AND o.ordernr = pr.ordernr
GROUP BY c.customer_name
The result of the sales_price and purchase_price is far too high. I seem to be getting double counts. What am I doing wrong? Is it possible to perform this in a single query?
Thank for your response!
It seems that the problem is that when you join the orders table to the tables with sales rates and purchase rates, you are getting the cartesian product of these two latter tables. I.e each row in these two tables are repeated once for each correponding row in the other table. The following query should solve this problem by summing the rates for each order before joining the sales rates and purchase rates to the other tables:
SELECT c.customernr, c.customer_name,
SUM(sr.sales_price) AS sales_price,
SUM(pr.purchase_price) AS purchase_price
FROM customers c
INNER JOIN orders o
ON o.customernr = c.customernr
LEFT JOIN (SELECT ordernr, SUM sales_price) AS sales_price
FROM sales_rates
GROUP BY ordernr) sr
ON sr.ordernr = o.ordernr
LEFT JOIN (SELECT ordernr, SUM(purchase_price) AS purchase_price
FROM purchase_rates
GROUP BY ordernr) pr
ON pr.ordernr = o.ordernr
GROUP BY c.customernr, c.customer_name;
It doesn't look like you are grouping by the customer. C.customerid or something like that.
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.