期中考试前准备--数据库修改代码

import java.sql.*;

import java.util.Scanner;

public class jdbcupdate {
	public static void main(String[]args) {
		final String URL = "jdbc:mysql://localhost:3306/test";
		final String USERNAME = "root";
	    final String PWD = "12345";
	    Connection connection = null;
	    Statement  stmt = null;
		Scanner con=new Scanner(System.in);
		String idnumber;
		String classname;
		String teachername;
		String didian;
		
		//idnumber=con.nextLine();
		classname=con.nextLine();
		teachername=con.nextLine();
		//didian=con.nextLine();
		try {
			// a.导入驱动，加载具体的驱动类
			Class.forName("com.mysql.jdbc.Driver");// 加载具体的驱动类
			// b.与数据库建立连接
			connection = DriverManager.getConnection(URL, USERNAME, PWD);
			stmt = connection.createStatement();
			
			
			//删除时如果是中文汉字要加单引号,如果是变量的话需要双引号单引号双引号
			String sql = "update student set teacher='"+teachername+"' where classname='"+classname+"'";
			// 执行SQL
			int count = stmt.executeUpdate(sql); 
			
			
			
			// d.处理结果
			if (count > 0) {  
				System.out.println("操作成功！");
			}
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		} catch(Exception e) {
			e.printStackTrace();
		}
		finally {
			try {
				 if(stmt!=null) stmt.close();// 对象.方法
				 if(connection!=null)connection.close();
			}catch(SQLException e) {
				e.printStackTrace();
			}
		}
	}


}