Question: How many users who are between 20 and 60 use phone brand of TCL?
SQL: SELECT COUNT(T1.device_id) FROM gender_age AS T1 INNER JOIN phone_brand_device_model2 AS T2 ON T1.device_id = T2.device_id WHERE T1.age BETWEEN 20 AND 60 AND T2.phone_brand = 'TCL'