John attended Math exam 1 time, Physics exam 1 time and Programming exam 1 time. 三、SQL 语句 3.1 自己写的 WITHtmpAS(SELECTa.student_id,b.subject_nameFROM(SELECTstudent_idFROMStudents)ASaCROSSJOINSubjectsASb),tmp1AS(SELECTstudent_id,subject_name,COUNT(*)ASattended_examsFROMExaminationsGROUPBYstu...