Java实现CRUD操作

Java实现CURD操作，最基础的版本

import org.junit.Test;

import java.sql.*;

public class JDBCDemo01 {
    public static void main(String[] args) {
//        testSelect();
//        testInsert();
//        testUpdate();
        testDelete();
    }

    //删除
    public static void testDelete(){
        Connection connection = null;
        Statement statement = null;
        ResultSet resultSet = null;

        try {
            Class.forName("com.mysql.cj.jdbc.Driver");

            String url = "jdbc:mysql://localhost:3306/db1?useSSL=false&serverTimezone=UTC";
            connection = DriverManager.getConnection(url, "root", "123456");

            String sql = "delete from orderlist where id=9";
            statement = connection.createStatement();
            int row = statement.executeUpdate(sql);     //进行添加行数，返回影响行数
            System.out.println(row);

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            try {
                statement.close();
                connection.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }

        }

    }


    //修改
    public static void testUpdate(){
        Connection connection = null;
        Statement statement = null;
        ResultSet resultSet = null;

        try {
            Class.forName("com.mysql.cj.jdbc.Driver");

            String url = "jdbc:mysql://localhost:3306/db1?useSSL=false&serverTimezone=UTC";
            connection = DriverManager.getConnection(url, "root", "123456");

            String sql = "update orderlist set uid='100' where id=9";
            statement = connection.createStatement();
            int row = statement.executeUpdate(sql);     //进行添加行数，返回影响行数
            System.out.println(row);

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            try {
                statement.close();
                connection.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }

        }

    }


    //添加
    public static void testInsert(){
        Connection connection = null;
        Statement statement = null;
        ResultSet resultSet = null;

        try {
            Class.forName("com.mysql.cj.jdbc.Driver");

            String url = "jdbc:mysql://localhost:3306/db1?useSSL=false&serverTimezone=UTC";
            connection = DriverManager.getConnection(url, "root", "123456");

            String sql = "insert into orderlist (id, number, uid) values (5, 1005, 3)";
            statement = connection.createStatement();
            int row = statement.executeUpdate(sql);     //进行添加行数，返回影响行数
            System.out.println(row);

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            try {
                statement.close();
                connection.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }

        }

    }



    //查询
    public static void testSelect() {
        Connection connection = null;
        Statement statement = null;
        ResultSet resultSet = null;


        try {
            // 加载驱动
            Class.forName("com.mysql.cj.jdbc.Driver");
            // 创建连接
            /*
            * @param url a database url of the form
             * jdbc:subprotocol:subname
             * @param user the database user on whose behalf the connection is being
             *   made
             * @param password the user's password
            * */
            String url = "jdbc:mysql://localhost:3306/db1?useSSL=false&serverTimezone=UTC";
            connection = DriverManager.getConnection(url, "root", "123456");

            // 编写sql,创建statement，执行sql语句
            String sql = "select * from orderlist";
            statement = connection.createStatement();
            resultSet = statement.executeQuery(sql);

            // 查询返回结果，遍历打印
            while (resultSet.next()){
                int id = resultSet.getInt("id");
                String number = resultSet.getString("number");
                int uid = resultSet.getInt("uid");
                System.out.println(id + " " + number + " " + uid);
            }

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            // 关闭资源
            try {
                resultSet.close();
                statement.close();
                connection.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
    }
}