MySQL练习题
创建下列表并创建相关约束 问题 1:查询出成绩表,而且student_id 后面要有对应的学生名,course_id 后面要有对应的课程名. 1 SELECT 2 score.sid, 3 score.student_id, 4 student.sname, 5 score.course_id, 6 course.cname, 7 score.number 8 FROM score 9 LEFT JOIN student 10 ON student.sid = score.student_id 11 LEFT JOIN course 12 ON course.cid = score.course_id 参考答案 2:查询平均成绩大于60分的同学的学号和平均成绩 1 SELECT student_id,SUM(number)/COUNT(student_id) AS avg_number FROM score GROUP BY student_id HAVING avg_number>60; View Code 3:查询所有同学的学号、姓名、选课数、总成绩 1 SELECT student.sid,student.sname,COUNT(score.student_id),SUM(number) FROM student,score WHERE student.sid=score