jdbc-mysql链接-基础版

Posted 2020-12-06 黑夜之鹰

1、基础连接代码
public static void main(String[] args) throws SQLException {

    String url = "jdbc:mysql://127.0.0.1:3306/student";
    String userName = "root";
    String password = "11111";
    String sql = "select id,name,age from user;";

    // 1.建立连接
    Connection connection = DriverManager.getConnection(url, userName, password);

    // 2.具体操作
    // 2.1 预编译 SQL
    PreparedStatement statement = connection.prepareStatement(sql);
    // 2.2 执行查询
    ResultSet resultSet = statement.executeQuery();
    // 2.3 处理结果集
    while (resultSet.next()) {
        int id = resultSet.getInt("id");
        String name = resultSet.getString("name");
        int age = resultSet.getInt("age");
        System.out.println("id = " + id + ", name=" + name + ", age=" + age);
    }

    // 3.资源关闭
    resultSet.close();
    statement.close();
    connection.close();
}

2、基础连接增删改查-加异常处理

static String URL = "jdbc:mysql://127.0.0.1:3306/student?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=UTC";

static String USER_NAME = "root";
static String PASSWORD = "123456";

public static void main(String[] args) {
    // testInsert1();

    testInsert2();

    // testUpdate();

    // insert , update , delete 操作时只有SQL和数据不一样，其他步骤都一样，所以可以归为一类操作
}

private static void testInsert1() {
    // 使用中文时，有字符编码问题
    String sql = "insert into `tb_user`(`name`,`age`) values(‘jim‘,‘66‘)";

    Connection connection = null;
    PreparedStatement statement = null;

    try {
        // 建立连接
        connection = DriverManager.getConnection(URL, USER_NAME, PASSWORD);

        // 创建statement 并执行update
        statement = connection.prepareStatement(sql);
        int effectRows = statement.executeUpdate();

        System.out.println("insert effectRows = " + effectRows);

    } catch (SQLException e) {
        e.printStackTrace();
    } finally {
        if (statement != null) {
            try {
                statement.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

private static void testInsert2() {
    // 使用中文时，有字符编码问题. TODO : 字符集编码问题需要设置一下
    String sql = "INSERT INTO `tb_user`(`name`,`age`) VALUES(?,?)";

    Connection connection = null;
    PreparedStatement statement = null;

    try {
        // 建立连接
        connection = DriverManager.getConnection(URL, USER_NAME, PASSWORD);

        // 创建statement 并执行update
        statement = connection.prepareStatement(sql);
        statement.setString(1, "王五");
        statement.setInt(2, 67);
        int effectRows = statement.executeUpdate();

        System.out.println("insert effectRows = " + effectRows);

    } catch (SQLException e) {
        e.printStackTrace();
    } finally {
        if (statement != null) {
            try {
                statement.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

private static void testUpdate() {
    // 使用中文时，有字符编码问题
    String sql = "update tb_user set name=‘haha‘ where id=6";

    Connection connection = null;
    PreparedStatement statement = null;

    try {
        // 建立连接
        connection = DriverManager.getConnection(URL, USER_NAME, PASSWORD);

        // 创建statement 并执行update
        statement = connection.prepareStatement(sql);
        int effectRows = statement.executeUpdate();

        System.out.println("update effectRows = " + effectRows);

    } catch (SQLException e) {
        e.printStackTrace();
    } finally {
        if (statement != null) {
            try {
                statement.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}