Tech for good

with cte as ( select feature_id, user_id, max(step_reached) as max_step from facebook_product_features_realizations group by feature_id, user_id)select f.feature_id, ifnull(avg(cte.max_step/f.n_steps)*100, 0) avg_percentagefrom facebook_product_features fleft join cte on f.feature_id = cte.feature_idgroup by f.feature_id;

# Solution 1SELECT COUNT(*) AS n_approvedFROM facebook_friendship_requestsWHERE MONTH(date_approved) IN(1,2);# Solution 2SELECT COUNT(*) AS n_approvedFROM facebook_friendship_requestsWHERE date_approved IS NOT NULLAND DATE_FORMAT(date_approved, '%Y-%m') IN ('2019-01', '2019-02');

with cte as ( select day, user1 from facebook_user_interactions union all select day, user2 as user1 from facebook_user_interactions) select day, count(*)/2, count(distinct user1)from ctegroup by day;

# Soltuion 1SELECT ROUND( (SELECT COUNT(*) FROM facebook_messages_received) / (SELECT COUNT(*) FROM facebook_messages_sent), 2 ) AS success_ratio;# Solution 2SELECT (SELECT COUNT(*) FROM facebook.messages.received) / (SELECT COUNT(*) FROM facebook.messages.sent) AS received_to_sent_ratio;