checkenrol.java

一个学生课绩管理系统

package database;

import java.sql.*;

public class checkEnrol {

	// 是否完成预修课
	public boolean hasPassPrepare(String prepare) {
		boolean f = false;
		int a = 0;
		String temp = null;
		String sql = "select score " + "from enrol,classes ,course "
				+ "where   enrol.class_id=classes.id "
				+ "and classes.cour_id=course.id " + "and course.id='"
				+ prepare + "' ";
		sqlBean db = new sqlBean();
		try {
			ResultSet rs = db.executeQuery(sql);
			if (rs.next())
				temp = rs.getString("score");
		} catch (SQLException e) {
			System.out.print(e.toString());
		}
		if (temp == null || temp.equals(""))
			return false;
		else {
			try {
				a = Integer.parseInt(temp);
			} catch (NumberFormatException e) {
				System.out.print(e.toString());
			}
			if (a >= 60)
				f = true;
		}
		return f;
	}

	// 该学生是否已经注册该课程
	public boolean hasLogin(String stu_id, String cour_id) {
		boolean f = true;
		String sql = "select stu_id,class_id " + "from enrol,classes "
				+ "where stu_id='" + stu_id + "' "
				+ "and classes.id=enrol.class_id " + "and cour_id='" + cour_id
				+ "' ";
		sqlBean db = new sqlBean();
		try {
			ResultSet rs = db.executeQuery(sql);
			if (rs.next()) {
				f = false;
			} else {
				f = true;
			}
		} catch (Exception e) {
			e.getMessage();
		}
		return f;
	}

	public ResultSet getCourse(String stu_id) {
		String sql = "select DISTINCT course.id,course.name,course.prepare,course.dep , "
				+ "classes.id as class_id,classes.room_id,classes.cour_time,teacher.name as tea_name "
				+ "from course,classes,teacher "
				+ "where classes.cour_id=course.id  "
				+ "and classes.tea_id=teacher.id "
				+ "and classes.id in "
				+ "( select classes.id from classes,student,course  "
				+ "where classes.id not in( select class_id from enrol where stu_id='"
				+ stu_id
				+ "') "
				+ "and ( student.department=course.dep or course.dep ='public')  "
				+ "and course.id=classes.cour_id and student.id='"
				+ stu_id
				+ "') ";

		sqlBean db = new sqlBean();
		ResultSet rs = db.executeQuery(sql);
		return rs;
	}

	public String getTotalMark(String id) {
		String temp = "0";
		String sql = "select mark from student where id='" + id + "'  ";
		sqlBean db = new sqlBean();
		ResultSet rs = db.executeQuery(sql);
		try {
			if (rs.next())
				temp = rs.getString("mark");
		} catch (Exception e) {
		}
		return temp;
	}

	public int updatestu(String pw, String id, String e_mail, String tel) {
		int num = 0;

		String sql = "update student set password='" + pw + "',e_mail='"
				+ e_mail + "',tel='" + tel + "'  where id='" + id + "'  ";
		sqlBean db = new sqlBean();
		num = db.executeUpdate(sql);
		return num;

	}

	public int enrol(String class_id, String stu_id) {
		int num = 0;
		String sql = "insert into enrol(stu_id,class_id) " + " VALUES('"
				+ stu_id + "','" + class_id + "')   ";
		sqlBean db = new sqlBean();
		num = db.executeUpdate(sql);
		return num;
	}

}