Friend Request Acceptance Rate

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Medium

Description

You are given a table of friend request actions. Each row represents either a 'sent' or 'accepted' action between a sender and a receiver. Write a SQL query to find for each sender: the total number of requests sent, the total number accepted, and the acceptance rate (accepted / sent), rounded to 2 decimal places. Senders with zero accepted requests should still appear with an acceptance rate of 0.00. Return the result ordered by sender_id. Note: You can assume that for every 'accepted' row, a corresponding 'sent' row exists for the same sender_id and receiver_id pair. Table: FriendRequests

Column Name	Type	Description
sender_id	INT	ID of the user who sent the request
receiver_id	INT	ID of the user who received it
action	VARCHAR	'sent' or 'accepted'
action_date	DATE	Date of the action

Database Schema (Inferred)

FriendRequests

Column Name	Example Value
sender_id	1
receiver_id	2
action	sent
action_date	2023-01-01

Example

FriendRequests

sender_id	receiver_id	action	action_date
1	2	sent	2023-01-01
1	2	accepted	2023-01-02
1	3	sent	2023-01-03
2	3	sent	2023-01-04
2	3	accepted	2023-01-05
2	4	sent	2023-01-06
3	4	sent	2023-01-07

Output

sender_id	total_sent	total_accepted	acceptance_rate
1	2	1	0.5
2	2	1	0.5
3	1	0	0

Explanation:

Sender 1 sent 2 requests, 1 accepted → rate 0.50. Sender 2 sent 2, 1 accepted → 0.50. Sender 3 sent 1, none accepted → 0.00.

Approach hint

Start with a simple approach, explain the trade-off, then move toward a cleaner or more scalable solution.

Common mistake

Skipping assumptions, edge cases, or trade-offs can make an otherwise good answer feel incomplete.