db.java

我实习时候的设计

package cn.yyl.lei;



import java.sql.*;//引用数据库操作包

import cn.yxh.util.DBConn;




public class DB {

	private Connection conn = null;//建立数据库连接对象

	private PreparedStatement stmt = null;//建立数据库操作对象

	private ResultSet rs = null;//建立结果集（用来接收从数据库中查询出来的数据）
	
	private Statement st=null;

	
	public  void updatestu(String studentid,String password,String name,String sex,String department)
	{
		conn=DBConn.getConn();
		try {
			stmt=conn.prepareStatement("update student set name=?,sex=?,department=?,password=? where studentid=? ");
			stmt.setString(1, name);
			stmt.setString(2, sex);
			stmt.setString(3, department);
			stmt.setString(5, studentid);
			stmt.setString(4, password);
			stmt.execute();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	public void savestu(String studentid,String password,String name,String sex,String department)
	{
		conn=DBConn.getConn();
		try {
			stmt=conn.prepareStatement("insert into student (studentid,password,name,sex,department) values(?,?,?,?,?)");//(studentid,password,name,sex,department) 
			stmt.setString(1, studentid);
			stmt.setString(2, password);
			stmt.setString(3, name);
			stmt.setString(4, sex);
			stmt.setString(5, department);		
			stmt.execute();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	
	}

	public ResultSet showstu(String name)
	{
		conn=DBConn.getConn();
		try {
			stmt=conn.prepareStatement("select * from student where name like ?");
			stmt.setString(1, "%"+name+"%");
			rs=stmt.executeQuery();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return rs;
		
	}
	  public ResultSet showallstudent()//显示所有学生记录
	    {
	    	
	    	conn=DBConn.getConn();
	    	try {
				stmt=conn.prepareStatement("select * from student");
				rs=stmt.executeQuery();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			return rs;
	    }
	    public ResultSet showstudent(String studentid)//以学号为关键字返回学生信息
	    {
	    	conn=DBConn.getConn();
	    	try {
				stmt=conn.prepareStatement("select * from student where studentid=?");
			    stmt.setString(1,studentid);
			    rs=stmt.executeQuery();
	    	} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			return rs;
	    }
	    public void delstu(String studentid)//删除课程记录
	    {
	 	   conn=DBConn.getConn();
	 	   try {
	 		stmt=conn.prepareStatement("delete from student where studentid=?");
	 		stmt.setString(1,studentid);
	 		stmt.execute();
	 	} catch (SQLException e) {
	 		// TODO Auto-generated catch block
	 		e.printStackTrace();
	 	}
	    }



}