学生选课信息管理系统（jsp+servlet+mysql）

package stuman; import java.sql.*; public class determine{ public ResultSet getClass(String tea_id){ String sql="select classes.id,course.name "+ "from classes,course "+ "where course.id=classes.cour_id "+ "and classes.tea_id='"+tea_id+"' "; sqlBean sqlbean = new sqlBean(); ResultSet rs = sqlbean.executeQuery(sql); return rs; } public ResultSet getStudents(String class_id){ String sql="select student.id,name ,department,sex,mark,e_mail,tel "+ "from student,enrol,classes "+ "where student.id=enrol.stu_id "+ "and enrol.accept='0' "+ "and classes.id=enrol.class_id "+ "and classes.id='"+class_id+"' "; sqlBean sqlbean = new sqlBean(); ResultSet rs = sqlbean.executeQuery(sql); return rs; } public ResultSet getStudents2(String class_id){ String sql="select student.id,name ,department,sex,mark,e_mail,tel "+ "from student,enrol,classes "+ "where student.id=enrol.stu_id "+ "and enrol.accept='1' "+ "and enrol.score='0' "+ "and classes.id=enrol.class_id "+ "and classes.id='"+class_id+"' "; sqlBean sqlbean = new sqlBean(); ResultSet rs = sqlbean.executeQuery(sql); return rs; } public int enrol(String stu_id,String class_id){ int num=0; String sql="update enrol set accept=1 "+ "where stu_id='"+stu_id+"' "+ "and class_id='"+class_id+"' "; sqlBean db = new sqlBean(); num=db.executeInsert(sql); return num; } public int marking(String stu_id,String class_id,String score){ int num=0; String sql="update enrol "+ "set score='"+score+"' "+ "where stu_id='"+stu_id+"' "+ "and class_id='"+class_id+"' "; sqlBean db = new sqlBean(); num=db.executeInsert(sql); return num; } public int addMark(String stu_id,String class_id){ int num=0; String sql="update student "+ "set student.mark=course.mark "+ "from student,course,classes "+ "where student.id='"+stu_id+"' "+ "and course.id=classes.cour_id "+ "and classes.id='"+class_id+"' "; sqlBean db = new sqlBean(); num=db.executeInsert(sql); return num; } }