【JavaWeb】1.jdbc的操作步骤

使用 mysql-connector-java.jar

// 删除
public void test01() throws ClassNotFoundException, SQLException {
    //1.注册驱动
    Class.forName("com.mysql.jdbc.Driver");//jar 5.1
    Class.forName("com.mysql.cj.jdbc.Driver");//jar 8
    
    //2.创建数据库连接
    String url = "jdbc:mysql://localhost:3306/jgs1904?useSSL&serverTimezone=GMT%2B8";
    String user = "root";
    String password = "root";
    Connection conn = DriverManager.getConnection(url, user, password);
    
    //3. 编写sql语句
    String sql = "delete from user where id = 1";
    
    //4. 创建sql语句执行者
    Statement stmt = conn.createStatement();
    
    //5. 执行sql语句
    int result = stmt.executeUpdate(sql);
    
    System.out.println(result);
    
    //6. 释放资源
    stmt.close();
    conn.coose();
}

//查询
public void test02(){
    //---获取数据库连接conn
    Statement stmt = conn.createStatement();
    //执行sql语句
    ResultSet rs = stmt.executeQuery("select * from user");
    //获取结果集的数据
    while(rs.next()){
        long id = rs.getLong("id");
        String username = rs.getString("username");
        String pwd = rs.getString("password");
    }
    
    //释放资源
    rs.close();
    stmt.close();
    conn.close();
}

//批处理
//---获取数据库连接conn对象
Statement stmt = conn.createStatement();

//添加批处理语句
stmt.addBatch("delete from user where id = 2");
stmt.addBatch("insert into user values(null, 'user', 'user')");
stmt.addBatch("update user set username = 'root' where id = 3");

//执行批处理语句
int[] result = stmt.executeBatch();

for(int i : result) {
    System.out.println(i);
}

stmt.close();
con.close();