1．　　在课程表中导入3条数据，写出sql语句和数据 2．　　在学生表中导入15条学生资料，每个班级5条数据，写出sql语句和数据 3．　　在成绩表中，每个学生每个课程1条数据，每个学生全选了课程表所有的课程，写出sql语句和数据-1. The courses table into three data and write sql statement and data 2. Students in the table into 15 students, each class 5 data and write sql statement and data 3. The results table, each student each course a data, each elected by the students of the curriculum of all courses, write sql statement and data