第二次作业：MySQL数据库及Java操作MySQL数据库

 把mysql与java连接的jar（mysql-connector-java-5.1.6-bin.jar）包导入工程.
package com.cn.edu;

    import java.beans.Statement;
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;  

    public class helloworld {
        private Connection conn = null;
        PreparedStatement statement = null;  

        // connect to MySQL
        void connSQL() {
            String url = "jdbc:mysql://localhost:3306/hello?characterEncoding=UTF-8";
            String username = "root";
            String password = "root"; // 加载驱动程序以连接数据库
            try {
                Class.forName("com.mysql.jdbc.Driver" );
                conn = DriverManager.getConnection( url,username, password );
                }
            //捕获加载驱动程序异常
             catch ( ClassNotFoundException cnfex ) {
                 System.err.println(
                 "装载 JDBC/ODBC 驱动程序失败。" );
                 cnfex.printStackTrace();
             }
             //捕获连接数据库异常
             catch ( SQLException sqlex ) {
                 System.err.println( "无法连接数据库" );
                 sqlex.printStackTrace();
             }
        }  

        // disconnect to MySQL
        void deconnSQL() {
            try {
                if (conn != null)
                    conn.close();
            } catch (Exception e) {
                System.out.println("关闭数据库问题 ：");
                e.printStackTrace();
            }
        }  

        // execute selection language
        ResultSet selectSQL(String sql) {
            ResultSet rs = null;
            try {
                statement = conn.prepareStatement(sql);
                rs = statement.executeQuery(sql);
            } catch (SQLException e) {
                e.printStackTrace();
            }
            return rs;
        }  

        // execute insertion language
        boolean insertSQL(String sql) {
            try {
                statement = conn.prepareStatement(sql);
                statement.executeUpdate();
                return true;
            } catch (SQLException e) {
                System.out.println("插入数据库时出错：");
                e.printStackTrace();
            } catch (Exception e) {
                System.out.println("插入时出错：");
                e.printStackTrace();
            }
            return false;
        }
        //execute delete language
        boolean deleteSQL(String sql) {
            try {
                statement = conn.prepareStatement(sql);
                statement.executeUpdate();
                return true;
            } catch (SQLException e) {
                System.out.println("插入数据库时出错：");
                e.printStackTrace();
            } catch (Exception e) {
                System.out.println("插入时出错：");
                e.printStackTrace();
            }
            return false;
        }
        //execute update language
        boolean updateSQL(String sql) {
            try {
                statement = conn.prepareStatement(sql);
                statement.executeUpdate();
                return true;
            } catch (SQLException e) {
                System.out.println("插入数据库时出错：");
                e.printStackTrace();
            } catch (Exception e) {
                System.out.println("插入时出错：");
                e.printStackTrace();
            }
            return false;
        }
        // show data in ju_users
        void layoutStyle2(ResultSet rs) {
            System.out.println("-----------------");
            System.out.println("执行结果如下所示:");
            System.out.println("-----------------");
            System.out.println(" 用户ID" + "/t/t" + "淘宝ID" + "/t/t" + "用户名"+ "/t/t" + "密码");
            System.out.println("-----------------");
            try {
                while (rs.next()) {
                    System.out.println(rs.getInt("ju_userID") + "/t/t"
                            + rs.getString("taobaoID") + "/t/t"
                            + rs.getString("ju_userName")
                             + "/t/t"+ rs.getString("ju_userPWD"));
                }
            } catch (SQLException e) {
                System.out.println("显示时数据库出错。");
                e.printStackTrace();
            } catch (Exception e) {
                System.out.println("显示出错。");
                e.printStackTrace();
            }
        }  

        public static void main(String args[]) {  

            helloworld h = new helloworld();
            h.connSQL();
            String s = "select * from ju_users";  

            String insert = "insert into ju_users(ju_userID,TaobaoID,ju_userName,ju_userPWD) values("+8329+","+34243+",'mm','789')";
            String update = "update ju_users set ju_userPWD =123 where ju_userName= 'mm'";
            String delete = "delete from ju_users where ju_userName= 'mm'";  

            if (h.insertSQL(insert) == true) {
                System.out.println("insert successfully");
                ResultSet resultSet = h.selectSQL(s);
                h.layoutStyle2(resultSet);
            }
            if (h.updateSQL(update) == true) {
                System.out.println("update successfully");
                ResultSet resultSet = h.selectSQL(s);
                h.layoutStyle2(resultSet);
            }
            if (h.insertSQL(delete) == true) {
                System.out.println("delete successfully");
                ResultSet resultSet = h.selectSQL(s);
                h.layoutStyle2(resultSet);
            }  

            h.deconnSQL();
        }
    }  

1、创建数据库

create databasecwq

go

2、连接数据库

use cwq

go

3、创建数据表

命令：create table <表名> ( <字段名1> <类型1> [,..<字段名n> <类型n>]);

建立一个名为Class的表

mysql> create table Class(

> id int(4) not null primary key auto_increment,

> name char(20) not null,

> sex int(4) not null default ‘0‘,

> degree double(16,2));

4、删除数据表

drop table cwq