How many businesses in Glendale city that are still running is opened from 8AM to 6PM?
still running refers to active = 'true'; opened from 8AM to 6PM refers to opening_time = '8AM' AND closing_time = '6PM';
SELECT COUNT(T1.category_name) FROM Categories AS T1 INNER JOIN Business_Categories AS T2 ON T1.category_id = T2.category_id INNER JOIN Business AS T3 ON T2.business_id = T3.business_id INNER JOIN Business_Hours AS T4 ON T3.business_id = T4.business_id WHERE T3.city LIKE 'Glendale' AND T4.opening_time LIKE '8AM' AND T4.closing_time LIKE '6PM'