ในด้านใดที่ฉันได้รับ B+ มากที่สุด ?ไม่จำเป็นต้องใช้ตารางทั้งหมด
In which area have I earned the most B+ 's ?It is not neccessary to use all the tables.
 course_prerequisite:  pre_course_id [ int]  course_id [ int] 
SELECT DISTINCT DERIVED_TABLEalias0.DERIVED_FIELDalias1 FROM (SELECT AREAalias0.area, COUNT(*) INNER JOIN student_record ON student_record.course_id = AREAalias0.course_id WHERE student_record.grade LIKE 'B+' AND student_record.student_id = 1 GROUP BY AREAalias0.area) AS DERIVED_TABLEalias0 WHERE DERIVED_TABLEalias0.DERIVED_FIELDalias1 = (SELECT COUNT(*) AS DERIVED_FIELDalias2 FROM area AS AREAalias1, student_record AS STUDENT_RECORDalias1 WHERE STUDENT_RECORDalias1.course_id = AREAalias1.course_id AND STUDENT_RECORDalias1.grade LIKE 'B+' AND STUDENT_RECORDalias1.student_id = 1 GROUP BY AREAalias1.area ORDER BY DERIVED_FIELDalias2 DESC LIMIT 1)