mysqli_connect和mysql_connect的区别
各位师哥师姐,哪位有时间给俺详细讲下mysqli和mysql的区别啊。俺是新手,看着迷糊。
我用mysqli查询数据库输出的时候出现乱码,不知道怎么解决了。看别人写的代码,如果用mysql的话可以用mysql_query("set names 'GBK'") 改变编码,如果直接改成mysqli_query("set names 'GBK'")会报错,无奈了。
------解决方案--------------------
mysqli_set_charset('连接数据库','你设置的编码');
------解决方案--------------------
一:Mysqli.dll是一个允许以对象的方式或者过程操作数据库的,它的使用方式也很容易。这里就几个常见的操作和mysql.dll做一个对比。
1:mysql.dll(可以理解为函数式的方式):
$conn = mysql_connect('localhost', 'user', 'password'); //连接mysql数据库
mysql_select_db('data_base'); //选择数据库
$result = mysql_query('select * from data_base');//这里有第二个可选参数,指定打开的连接
$row = mysql_fetch_row( $result ) ) //为了简单,这里只取一行数据
echo $row[0]; //输出第一个字段的值
mysqli也有过程式的方式,只不过开始贯以mysqli的前缀,其他都差不多。如果mysqli以过程式的方式操作的话,有些函数必须指定资源,比如说 mysqli_query(资源标识,SQL语句),并且资源标识的参数是放在前面的,而mysql_query(SQL语句,'可选')的资源标识是放在后面的,并且可以不指定,它默认是上一个打开的连接或资源。
2mysqli.dll(对象方式):
$conn = new mysqli('localhost', 'user', 'password','data_base');
//这里的连接是new出来的,最后一个参数是直接指定数据库,不用mysql_select_db()了
//也可以构造时候不指定,然后 $conn -> select_db('data_base')
$result = $conn -> query( 'select * from data_base' );
$row = $result -> fetch_row(); //取一行数据
echo row[0]; //输出第一个字段的值
二:mysql_fetch_row(),mysql_fetch_array()
这两个函数,返回的都是一个数组,区别就是第一个函数返回的数组是只包含值,我们只能$row[0],
$row[1],这样以数组下标来读取数据,而mysql_fetch_array()返回的数组既包含第一种,也包含键值
对的形式,我们可以这样读取数据,(假如数据库的字段是 username,passwd):
$row['username'], $row['passwd']
而且,如果用($row as $kay => $value)来操作的话,还以直接取得数据库的字段名称。
更主要的是mysqli是php5提供的新函数库,(i)表示改进,其执行速度更快.
-----------------------------------------
你的sql出错是因为你调用mysqli的方式不对
参考:
$conn = new mysqli('localhost', 'user', 'password','data_base');
//这里的连接是new出来的,最后一个参数是直接指定数据库,不用mysql_select_db()了
//也可以构造时候不指定,然后 $conn -> select_db('data_base')
$result = $conn -> query( 'select * from data_base' );

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.


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

SublimeText3 Linux new version
SublimeText3 Linux latest version

Dreamweaver Mac version
Visual web development tools

ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment

SecLists
SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

SublimeText3 Mac version
God-level code editing software (SublimeText3)