SQL CAPSTONE PROJECT

WITH months AS
(SELECT
'2017-01-01' as first_day,
'2017-01-31' as last_day
UNION
SELECT
'2017-02-01' as first_day,
'2017-02-28' as last_day
UNION
SELECT
'2017-03-01' as first_day,
'2017-03-31' as last_day
),
cross_join AS
(SELECT *
FROM subscriptions
CROSS JOIN months
),
status as
(SELECT id, first_day as 'month',
CASE WHEN (subscription_start < first_day)
AND (subscription_end > first_day)
OR (subscription_end IS NULL)
AND (segment = 87)
THEN 1
ELSE 0
END AS is_active_87,
CASE WHEN (subscription_start < first_day)
AND (subscription_end > first_day)
OR (subscription_end IS NULL)
AND (segment = 30)
THEN 1
ELSE 0
END AS is_active_30,
CASE
WHEN (subscription_end BETWEEN first_day AND last_day) AND (segment = 87) THEN 1
ELSE 0
END AS is_canceled_87,
CASE
WHEN (subscription_end BETWEEN first_day AND last_day) AND (segment = 30) THEN 1
ELSE 0
END AS is_canceled_30
FROM cross_join
),
status_aggregate AS
(SELECT month, SUM(is_active_87) AS 'sum_active_87',
SUM(is_active_30) AS 'sum_active_30',
SUM(is_canceled_87) AS 'sum_canceled_87',
SUM(is_canceled_30) AS 'sum_canceled_30'
FROM status
GROUP BY month
)
SELECT month,
1.0* sum_canceled_87/sum_active_87 AS 'churn_rate_87',
1.0* sum_canceled_30/sum_active_30 AS 'churn_rate_30'
from status_aggregate;

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