2205. The Number of Users That Are Eligible for Discount.py

2205. The Number of Users That Are Eligible for Discount
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SQL Schema
Table: Purchases

+-------------+----------+
| Column Name | Type     |
+-------------+----------+
| user_id     | int      |
| time_stamp  | datetime |
| amount      | int      |
+-------------+----------+
(user_id, time_stamp) is the primary key for this table.
Each row contains information about the purchase time and the amount paid for the user with ID user_id.
 

A user is eligible for a discount if they had a purchase in the inclusive interval of time [startDate, endDate] with at least minAmount amount. To convert the dates to times, both dates should be considered as the start of the day (i.e., endDate = 2022-03-05 should be considered as the time 2022-03-05 00:00:00).

Write an SQL query to report the number of users that are eligible for a discount.

The query result format is in the following example.

 

Example 1:

Input: 
Purchases table:
+---------+---------------------+--------+
| user_id | time_stamp          | amount |
+---------+---------------------+--------+
| 1       | 2022-04-20 09:03:00 | 4416   |
| 2       | 2022-03-19 19:24:02 | 678    |
| 3       | 2022-03-18 12:03:09 | 4523   |
| 3       | 2022-03-30 09:43:42 | 626    |
+---------+---------------------+--------+
startDate = 2022-03-08, endDate = 2022-03-20, minAmount = 1000
Output: 
+----------+
| user_cnt |
+----------+
| 1        |
+----------+
Explanation:
Out of the three users, only User 3 is eligible for a discount.
 - User 1 had one purchase with at least minAmount amount, but not within the time interval.
 - User 2 had one purchase within the time interval, but with less than minAmount amount.
 - User 3 is the only user who had a purchase that satisfies both conditions.
















CREATE FUNCTION getUserIDs(@startDate DATE, @endDate DATE, @minAmount INT) RETURNS INT AS
BEGIN
    RETURN (
        /* Write your T-SQL query statement below. */
          SELECT COUNT(DISTINCT user_id)
        FROM Purchases
        WHERE amount >= @minAmount
        AND time_stamp BETWEEN @startDate AND @endDate
        
    );
END