php连接数据库
/**************denglu.php****************/
session_start();
$username=$_POST['username'];
$password=$_POST['password'];
@ $db = mysql_connect('localhost','root','root'); //连接数据库
if (!$db) {
die('Could not connect: ' . mysql_error());
}
//echo '连接成功!';
mysql_select_db('wwj'); //选择数据库文件wwj
//执行SQL 语句
mysql_query("set names utf8");//数据库中是utf8 ,没有“-”.网页中有!!
$sql="select * from pre_common_member where username=$username";
$res=mysql_query($sql);
if($row=mysql_fetch_assoc($res)){
if($row['password']==md5($password)){
$name=$row['username'];
echo"<script>alert('登陆成功!')</script>";
session_register('$name');
header('Location:ClassWeb.php');exit();
}
}
echo"<script>alert('用户名或密码错误!')</script>";
header('Location:ClassWeb.php');exit();
mysql_free_result($res);
?>
我输入的账号的密码是对的,但是提示信息是乱码,我也不知道是登陆成功还是错误,提示窗口出现后,我点击确定,第二个警告错误才出现!!!!错误:
Warning: mysql_fetch_assoc(): supplied argument is not a valid MySQL result resource in F:\Apache HTTP Server\AppServ\www\ClassWeb\denglu.php on line 15
Warning: Cannot modify header information - headers already sent by (output started at F:\Apache HTTP Server\AppServ\www\ClassWeb\denglu.php:15) in F:\Apache HTTP Server\AppServ\www\ClassWeb\denglu.php on line 24
------解决思路----------------------
$sql="select * from pre_common_member where username='$username'";
------解决思路----------------------
弹窗乱码是因为你的程序文件不是 utf-8 的
错误信息是因为你在
header('Location:ClassWeb.php');
前有输出
echo"<script>alert('用户名或密码错误!')</script>";
------解决思路----------------------
php连接数据库显示示例
//数据库连接conn.php页面
$conn=mysql_connect("localhost","root","root"); //连接数据库服务器
mysql_select_db("db_forumm",$conn); //连接指定的数据库
mysql_query("set names gb2312"); //对数据库中的编码格式进行转换,避免出现中文乱码的问题
?>
//功能页面显示数据
$tb_forum_name=$_SESSION["tb_forum_name"];//记录用户名
if($tb_forum_name==""){
echo "<script>alert('您还没有登录!');window.location.href='index.php';</script>";//登录控制
exit;
}//codego.net/tags/4/1/
$sql=mysql_query("select * from tb_forum_user where tb_forum_name='".$tb_forum_name."'",$conn);
$info=mysql_fetch_array($sql);//选择数据库数据
?>

What’s still popular is the ease of use, flexibility and a strong ecosystem. 1) Ease of use and simple syntax make it the first choice for beginners. 2) Closely integrated with web development, excellent interaction with HTTP requests and database. 3) The huge ecosystem provides a wealth of tools and libraries. 4) Active community and open source nature adapts them to new needs and technology trends.

PHP and Python are both high-level programming languages that are widely used in web development, data processing and automation tasks. 1.PHP is often used to build dynamic websites and content management systems, while Python is often used to build web frameworks and data science. 2.PHP uses echo to output content, Python uses print. 3. Both support object-oriented programming, but the syntax and keywords are different. 4. PHP supports weak type conversion, while Python is more stringent. 5. PHP performance optimization includes using OPcache and asynchronous programming, while Python uses cProfile and asynchronous programming.

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP remains important in the modernization process because it supports a large number of websites and applications and adapts to development needs through frameworks. 1.PHP7 improves performance and introduces new features. 2. Modern frameworks such as Laravel, Symfony and CodeIgniter simplify development and improve code quality. 3. Performance optimization and best practices further improve application efficiency.

PHPhassignificantlyimpactedwebdevelopmentandextendsbeyondit.1)ItpowersmajorplatformslikeWordPressandexcelsindatabaseinteractions.2)PHP'sadaptabilityallowsittoscaleforlargeapplicationsusingframeworkslikeLaravel.3)Beyondweb,PHPisusedincommand-linescrip

PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values and handle functions that may return null values.


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