年份条件工作正常，但我运行年份和日期显示为null

SELECT Sum(gross_motor + visual_motor_skills 
       + draws_a_person + prints_personal_data) 
FROM   brigance_screening_term0 AS T0 
WHERE  year = 2011 
   AND Str_to_date(date, '%Y-%m-%d') = 2016 - 05 - 11 
LIMIT  1 
SELECT Sum(gross_motor + visual_motor_skills