Question

2082. The Number of Rich Customers

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Description

Table: Store

+-------------+------+
| Column Name | Type |
+-------------+------+
| bill_id   | int  |
| customer_id | int  |
| amount    | int  |
+-------------+------+
bill_id is the primary key (column with unique values) for this table.
Each row contains information about the amount of one bill and the customer associated with it.

 

Write a solution to report the number of customers who had at least one bill with an amount strictly greater than 500.

The result format is in the following example.

 

Example 1:

Input: 
Store table:
+---------+-------------+--------+
| bill_id | customer_id | amount |
+---------+-------------+--------+
| 6     | 1       | 549  |
| 8     | 1       | 834  |
| 4     | 2       | 394  |
| 11    | 3       | 657  |
| 13    | 3       | 257  |
+---------+-------------+--------+
Output: 
+------------+
| rich_count |
+------------+
| 2      |
+------------+
Explanation: 
Customer 1 has two bills with amounts strictly greater than 500.
Customer 2 does not have any bills with an amount strictly greater than 500.
Customer 3 has one bill with an amount strictly greater than 500.

Solutions

Solution 1

# Write your MySQL query statement below
SELECT
  COUNT(DISTINCT customer_id) AS rich_count
FROM Store
WHERE amount > 500;