refactor 1364

Author: fishercoder1534

database/_1364.sql

@@ -1,104 +1,3 @@
---1364. Number of Trusted Contacts of a Customer
---
---Table: Customers
---
---+---------------+---------+
---| Column Name   | Type    |
---+---------------+---------+
---| customer_id   | int     |
---| customer_name | varchar |
---| email         | varchar |
---+---------------+---------+
---customer_id is the primary key for this table.
---Each row of this table contains the name and the email of a customer of an online shop.
---
---
---Table: Contacts
---
---+---------------+---------+
---| Column Name   | Type    |
---+---------------+---------+
---| user_id       | id      |
---| contact_name  | varchar |
---| contact_email | varchar |
---+---------------+---------+
---(user_id, contact_email) is the primary key for this table.
---Each row of this table contains the name and email of one contact of customer with user_id.
---This table contains information about people each customer trust. The contact may or may not exist in the Customers table.
---
---
---
---Table: Invoices
---
---+--------------+---------+
---| Column Name  | Type    |
---+--------------+---------+
---| invoice_id   | int     |
---| price        | int     |
---| user_id      | int     |
---+--------------+---------+
---invoice_id is the primary key for this table.
---Each row of this table indicates that user_id has an invoice with invoice_id and a price.
---
---
---Write an SQL query to find the following for each invoice_id:
---
---customer_name: The name of the customer the invoice is related to.
---price: The price of the invoice.
---contacts_cnt: The number of contacts related to the customer.
---trusted_contacts_cnt: The number of contacts related to the customer and at the same time they are customers to the shop. (i.e His/Her email exists in the Customers table.)
---Order the result table by invoice_id.
---
---The query result format is in the following example:
---
---Customers table:
---+-------------+---------------+--------------------+
---| customer_id | customer_name | email              |
---+-------------+---------------+--------------------+
---| 1           | Alice         | alice@leetcode.com |
---| 2           | Bob           | bob@leetcode.com   |
---| 13          | John          | john@leetcode.com  |
---| 6           | Alex          | alex@leetcode.com  |
---+-------------+---------------+--------------------+
---Contacts table:
---+-------------+--------------+--------------------+
---| user_id     | contact_name | contact_email      |
---+-------------+--------------+--------------------+
---| 1           | Bob          | bob@leetcode.com   |
---| 1           | John         | john@leetcode.com  |
---| 1           | Jal          | jal@leetcode.com   |
---| 2           | Omar         | omar@leetcode.com  |
---| 2           | Meir         | meir@leetcode.com  |
---| 6           | Alice        | alice@leetcode.com |
---+-------------+--------------+--------------------+
---Invoices table:
---+------------+-------+---------+
---| invoice_id | price | user_id |
---+------------+-------+---------+
---| 77         | 100   | 1       |
---| 88         | 200   | 1       |
---| 99         | 300   | 2       |
---| 66         | 400   | 2       |
---| 55         | 500   | 13      |
---| 44         | 60    | 6       |
---+------------+-------+---------+
---Result table:
---+------------+---------------+-------+--------------+----------------------+
---| invoice_id | customer_name | price | contacts_cnt | trusted_contacts_cnt |
---+------------+---------------+-------+--------------+----------------------+
---| 44         | Alex          | 60    | 1            | 1                    |
---| 55         | John          | 500   | 0            | 0                    |
---| 66         | Bob           | 400   | 2            | 0                    |
---| 77         | Alice         | 100   | 3            | 2                    |
---| 88         | Alice         | 200   | 3            | 2                    |
---| 99         | Bob           | 300   | 2            | 0                    |
---+------------+---------------+-------+--------------+----------------------+
---Alice has three contacts, two of them are trusted contacts (Bob and John).
---Bob has two contacts, none of them is a trusted contact.
---Alex has one contact and it is a trusted contact (Alice).
---John doesn't have any contacts.
-
-
 --credit: https://leetcode.com/problems/number-of-trusted-contacts-of-a-customer/discuss/522435/mysql-simple-solution
 
 select i.invoice_id,