Measure Immediate Deliveries among Customers’ First Orders

### Problem Return immediate_percentage: the percentage of customers whose first order was immediate, rounded to two decimal places. An order is immediate exactly when order_date equals customer_pref_delivery_date. First means earliest order_date; the source guarantees exactly one first order for each customer. ### Tables Table: `Delivery` ```text +-----------------------------+---------+ | Column Name | Type | +-----------------------------+---------+ | delivery_id | int | | customer_id | int | | order_date | date | | customer_pref_delivery_date | date | +-----------------------------+---------+ delivery_id is the column of 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). ``` ### Constraints - In this version, `Delivery` contains at least one order, so at least one customer is represented. ### Example ```text Delivery (delivery_id,customer_id,order_date,customer_pref_delivery_date): (1,1,2021-01-01,2021-01-01), (2,1,2021-01-02,2021-01-04), (3,2,2021-01-01,2021-01-03), (4,2,2021-01-02,2021-01-02) Output (immediate_percentage): (50.00) ``` ### What a Strong Answer Covers - Use only the earliest order for each customer. - Classify first orders by their actual and preferred dates, then report the rounded percentage. ### Follow-up Questions - How would you report the metric separately for each first-order month? - How would you define the first order if several orders could share the earliest date?