Problem

Table: Delivery

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+-----------------------------+---------+
| Column Name                 | Type    |
+-----------------------------+---------+
| delivery_id                 | int     |
| customer_id                 | int     |
| order_date                  | date    |
| customer_pref_delivery_date | date    |
+-----------------------------+---------+

delivery_id is the primary key (column with unique values) of this table. The table holds information about food delivery to customers that make orders at some date and specify a preferred delivery date (on the same order date or after it).

If the customer’s preferred delivery date is the same as the order date, then the order is called immediate; otherwise, it is called scheduled.

Write a solution to find the percentage of immediate orders in the table, rounded to 2 decimal places.

The result format is in the following example.

Examples

Example 1:

Input: Delivery table:

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+-------------+-------------+------------+-----------------------------+
| delivery_id | customer_id | order_date | customer_pref_delivery_date |
+-------------+-------------+------------+-----------------------------+
| 1           | 1           | 2019-08-01 | 2019-08-02                  |
| 2           | 5           | 2019-08-02 | 2019-08-02                  |
| 3           | 1           | 2019-08-11 | 2019-08-11                  |
| 4           | 3           | 2019-08-24 | 2019-08-26                  |
| 5           | 4           | 2019-08-21 | 2019-08-22                  |
| 6           | 2           | 2019-08-11 | 2019-08-13                  |
+-------------+-------------+------------+-----------------------------+

Output:

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+----------------------+
| immediate_percentage |
+----------------------+
| 33.33                |
+----------------------+

Explanation: The orders with delivery id 2 and 3 are immediate while the others are scheduled.

Solution

Method 1 - Using Division and Round

Code

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SELECT ROUND(100*AVG(order_date = customer_pref_delivery_date), 2) AS immediate_percentage
FROM Delivery;
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import pandas as pd

def food_delivery(delivery: pd.DataFrame) -> pd.DataFrame:
    return pd.DataFrame({'immediate_percentage': [
        round(delivery[delivery['order_date'] == delivery['customer_pref_delivery_date']].size / delivery.size * 100, 2)
    ]})