CASE statement in SQL giving not proper values - mysql

Question

I am having abnormal values when I run this part in my sql code. SQL syntax wise, everything is okay with this?
select
COUNT(CASE WHEN bt.idBillingStatus = 2
THEN 1
ELSE NULL END) AS successfulbillinghits,
SUM(CASE WHEN bt.idBillingStatus = 2
THEN price
ELSE 0.0 END)
AS old_revenue
from table
Overall Query is this. The result of successfulbillinghits should be equal to timesbilled
SELECT
cs.idCustomerSubscription,
cs.msisdn,
pro.name AS promoterName,
c.name AS ClubName,
c.idClub AS ClubID,
o.name AS operatorName,
o.idOperator AS OperatorID,
co.name AS country,
-- cu.customerSince AS CustomerSince,
cs.subscribeddate AS subscribeddate,
-- cs.subscriptionNotificationSent AS SubNotificationSent,
-- cs.eventId AS EventId,
cs.unsubscribeddate AS unsubscribeddate,
cs.firstBillingDate AS FirstBillingDate,
cs.lastBilledDate As LastBilledDate,
cs.lastAttemptDate AS LastAttemptDate,
-- smp.code AS packageName,
-- o.mfactor AS mmfactor,
-- cs.idSubscriptionSource AS SubscriptionChannel,
-- cs.idUnsubscribeSource AS UnsubscriptionChannel,
-- DATE(bt.creationDate) AS BillingCreationDate,
-- bt.price AS pricePerBilling,
-- cs.lastRetryDate As LastRetryDate,
-- cs.lastRenewalDate AS LastRenewalDate,
-- cs.isActive AS ActiveStatus,
-- COUNT(bt.idBillingTransaction) AS BillingAttempts,
curr.idcurreny_symbol AS CurrencyID,
curr.symbol AS currency,
date(bt.creationDate) AS BillingDate,
cs.lastBilledAmount As LastBilledAmount,
cs.timesbilled,
price,
-- sum(price),
-- revenueShareAmountLocal,
-- o.mfactor,
-- count(IFF (bt.idBillingStatus = 2,1,0)) as otherversion,
count(CASE WHEN bt.idBillingStatus = 2
THEN 1
ELSE 0 END) AS successfulbillinghits,
SUM(CASE WHEN bt.idBillingStatus = 2
THEN price
ELSE 0.0 END)
AS old_revenue
FROM
customersubscription cs
LEFT JOIN
billing_transaction bt
ON CONVERT(cs.msisdn USING latin1) = bt.msisdn
AND cs.idClub = bt.idClub
AND bt.creationDate BETWEEN cs.SubscribedDate AND COALESCE(cs.UnsubscribedDate, now())
INNER JOIN customer cu ON (cs.idCustomer = cu.idcustomer)
INNER JOIN operator o ON (o.idoperator = cu.idoperator)
INNER JOIN country co ON (co.`idCountry` = o.idCountry)
INNER JOIN curreny_symbol curr ON (curr.idcurreny_symbol = co.idCurrencySymbol)
LEFT JOIN Promoter pro ON cs.idPromoter = pro.id
INNER JOIN club_operator_relationships cor ON cor.clubId = cs.idClub
INNER JOIN club c ON c.idClub = cs.idClub
-- INNER JOIN operator op ON op.idOperator = cu.idOperator
WHERE
-- (cs.timesbilled > 0 and cs.subscribeddate < '2016-09-01 00:00:00' )
cs.subscribeddate between '2017-04-20 00:00:00' and '2017-04-21 00:00:00'
AND cs.idClub IN (39)
GROUP BY idCustomerSubscription, ClubName, operatorName, promoterName
Successfulbillinghits is much greater than timesbilled in the result

Answer 1

Instead of COUNTuse SUM, as count counts blanks or nulls also
select
SUM(CASE WHEN bt.idBillingStatus = 2
THEN 1
ELSE 0 END) AS successfulbillinghits,
SUM(CASE WHEN bt.idBillingStatus = 2
THEN price
ELSE 0.0 END)
AS old_revenue
from table

Answer 2

Instead of using CASE, you can use WHERE clause with these aggregate functions, e.g.:
SELECT COUNT(*) as `successfulbillinghits`, SUM(price) as `old_revenue`
FROM table bt
WHERE bt.idBillingStatus = 2;