SELECT COUNT(DISTINCT SNO)FROM Student;SELECT MAX(Score)FROM ChooseWHERE CourseID = 'C1';SELECT MIN(Score)FROM ChooseWHERE CourseID = 'C1';SELECT SUM(Score)FROM ChooseWHERE CourseID = 'C1';SELECT AVG(Score)FROM ChooseWHERE CourseID = 'C1';SELECT CourseID,CourseNameFROM CourseWHERE CourseBeforeID IS NULL; SELECT Student.`SNO`,Student.`Name`,Course.`CourseName`,choose.`Score`FROM student,choose,courseWHERE choose.`SNO` = student.`SNO` AND course.`CourseID` = choose.`CourseID`;SELECT SNO,NAME,AgeFROM StudentWHERE College IN (SELECT College FROM Student WHERE NAME = '张三' );SELECT *FROM student stu1WHERE EXISTS (SELECT College FROM student WHERE stu1.`College` = college AND NAME = '张三' ); SELECT sno,scoreFROM chooseWHERE courseid='C1' and score<any(SELECT scorefrom choose,studentwhere student.sno=choose.sno and name='张三' and courseid='C1');SELECT SNO FROM chooseWHERE CourseID = 'C1'UNIONSELECT SNOFROM chooseWHERE CourseID = 'C3';