Interview Query

SMS Confirmations

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sms_sends table

column type
ds datetime
country string
carrier string
phone_number integer
type string

confirmers table

column type
date datetime
phone_number integer

We’re given two tables, one that represents SMS sends to phone numbers and the other represents confirmations from SMS sends. 

1. Write a query to calculate the number of unique phone numbers that we sent ‘confirmation’ SMS texts to on February 28th, 2020 by carrier and country.

Example: 

columns type
carrier string
country string
unique_numbers int

2. Calculate what percentage of users were confirmed per day.

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MySQL 8.0.17
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