php读取文件
1。php存文件的时候$testfilename2居然是非要单引号才行,要不然用双引号会报错,以后用变量的时候应该多用单引号
?
?
$testfilename2='D:\ProgramFiles2\AppServ\www\catch28\admin\testmethod6.html';//文件名,可以为.php或者.txt等文本文件
file_put_contents($testfilename,'');
2。mysql_free_result() 在update的操作的时候不需要调用:
mysql_free_result
(PHP 4, PHP 5)
mysql_free_result ― Free result memory
Description
mysql_free_result() will free all memory associated with the result identifier result.
mysql_free_result() only needs to be called if you are concerned about how much memory is being used for queries that return large result sets. All associated result memory is automatically freed at the end of the script's execution.
Parameters
?
The result resource that is being evaluated. This result comes from a call to mysql_query().
Return Values
Returns TRUE on success or FALSE on failure.
If a non-resource is used for the result, an error of level E_WARNING will be emitted. It's worth noting that mysql_query() only returns a resource for SELECT, SHOW, EXPLAIN, and DESCRIBE queries.
Examples
?
Example #1 A mysql_free_result() example
<span style="color: #000000;">
<span style="color: #0000bb;"><?php <br>$result?</span><span style="color: #007700;">=?</span><span style="color: #0000bb;">mysql_query</span><span style="color: #007700;">(</span><span style="color: #dd0000;">"SELECT?id,email?FROM?people?WHERE?id?=?'42'"</span><span style="color: #007700;">);<br>if?(!</span><span style="color: #0000bb;">$result</span><span style="color: #007700;">)?{<br>????echo?</span><span style="color: #dd0000;">'Could?not?run?query:?'?</span><span style="color: #007700;">.?</span><span style="color: #0000bb;">mysql_error</span><span style="color: #007700;">();<br>????exit;<br>}<br></span><span style="color: #ff8000;">/*?Use?the?result,?assuming?we're?done?with?it?afterwards?*/<br></span><span style="color: #0000bb;">$row?</span><span style="color: #007700;">=?</span><span style="color: #0000bb;">mysql_fetch_assoc</span><span style="color: #007700;">(</span><span style="color: #0000bb;">$result</span><span style="color: #007700;">);<br><br></span><span style="color: #ff8000;">/*?Now?we?free?up?the?result?and?continue?on?with?our?script?*/<br></span><span style="color: #0000bb;">mysql_free_result</span><span style="color: #007700;">(</span><span style="color: #0000bb;">$result</span><span style="color: #007700;">);<br><br>echo?</span><span style="color: #0000bb;">$row</span><span style="color: #007700;">[</span><span style="color: #dd0000;">'id'</span><span style="color: #007700;">];<br>echo?</span><span style="color: #0000bb;">$row</span><span style="color: #007700;">[</span><span style="color: #dd0000;">'email'</span><span style="color: #007700;">];<br></span><span style="color: #0000bb;">?></span>
</span>
Notes
Note: For backward compatibility, the following deprecated alias may be used: mysql_freeresult()
See Also
?
- mysql_query() - Send a MySQL query
- is_resource() - Finds whether a variable is a resource
If you need to use? mysql_free_result(), you may have received this error. What causes it and how can you fix it?
First, what is mysql_free_result()? When you make mySQL database queries that return large sets of data, it can cause your server to bog down because those results are hogging up a lot of memory. On a high-traffic site, it can actually crash your server as more and more of those results build up. So, mysql_free_result() is a built-in PHP function that releases the results of your query from memory. Again, this is usually not a big deal unless you are returning large data sets from your queries, but it is always good practice to clear your results and free up the memory on your server. Here is an example of what the PHP code might look like:
?
?
//...CONNECT TO DATABASE... $query = "SELECT * FROM employees WHERE age >= 30"; if ($result = mysql_query($query)) { while ($row = mysql_fetch_array($result)) { //...DO SOMETHING HERE... } mysql_free_result($result); //free the query results from memory } ///...CLOSE YOUR DATABSE CONNECTION...?But, if you have strict PHP warnings enabled on your server, you may start getting the warning above for some (but not all) of your queries. I had a really hard time tracking this problem down, but I finally found it here. You only use mysql_free_result() for the following query types: SELECT, SHOW, EXPLAIN, and DESCRIBE. So, if you perform an UPDATE query, it doesn’t return a valid resource and throws the warning when you call mysql_free_result(). Duh.

本篇文章给大家带来了关于mysql的相关知识,其中主要介绍了关于架构原理的相关内容,MySQL Server架构自顶向下大致可以分网络连接层、服务层、存储引擎层和系统文件层,下面一起来看一下,希望对大家有帮助。

在mysql中,可以利用char()和REPLACE()函数来替换换行符;REPLACE()函数可以用新字符串替换列中的换行符,而换行符可使用“char(13)”来表示,语法为“replace(字段名,char(13),'新字符串') ”。

mysql的msi与zip版本的区别:1、zip包含的安装程序是一种主动安装,而msi包含的是被installer所用的安装文件以提交请求的方式安装;2、zip是一种数据压缩和文档存储的文件格式,msi是微软格式的安装包。

方法:1、利用right函数,语法为“update 表名 set 指定字段 = right(指定字段, length(指定字段)-1)...”;2、利用substring函数,语法为“select substring(指定字段,2)..”。

转换方法:1、利用cast函数,语法“select * from 表名 order by cast(字段名 as SIGNED)”;2、利用“select * from 表名 order by CONVERT(字段名,SIGNED)”语句。

本篇文章给大家带来了关于mysql的相关知识,其中主要介绍了关于MySQL复制技术的相关问题,包括了异步复制、半同步复制等等内容,下面一起来看一下,希望对大家有帮助。

本篇文章给大家带来了关于mysql的相关知识,其中主要介绍了mysql高级篇的一些问题,包括了索引是什么、索引底层实现等等问题,下面一起来看一下,希望对大家有帮助。

在mysql中,可以利用REGEXP运算符判断数据是否是数字类型,语法为“String REGEXP '[^0-9.]'”;该运算符是正则表达式的缩写,若数据字符中含有数字时,返回的结果是true,反之返回的结果是false。


热AI工具

Undresser.AI Undress
人工智能驱动的应用程序,用于创建逼真的裸体照片

AI Clothes Remover
用于从照片中去除衣服的在线人工智能工具。

Undress AI Tool
免费脱衣服图片

Clothoff.io
AI脱衣机

AI Hentai Generator
免费生成ai无尽的。

热门文章

热工具

DVWA
Damn Vulnerable Web App (DVWA) 是一个PHP/MySQL的Web应用程序,非常容易受到攻击。它的主要目标是成为安全专业人员在合法环境中测试自己的技能和工具的辅助工具,帮助Web开发人员更好地理解保护Web应用程序的过程,并帮助教师/学生在课堂环境中教授/学习Web应用程序安全。DVWA的目标是通过简单直接的界面练习一些最常见的Web漏洞,难度各不相同。请注意,该软件中

PhpStorm Mac 版本
最新(2018.2.1 )专业的PHP集成开发工具

SublimeText3 Mac版
神级代码编辑软件(SublimeText3)

MinGW - 适用于 Windows 的极简 GNU
这个项目正在迁移到osdn.net/projects/mingw的过程中,你可以继续在那里关注我们。MinGW:GNU编译器集合(GCC)的本地Windows移植版本,可自由分发的导入库和用于构建本地Windows应用程序的头文件;包括对MSVC运行时的扩展,以支持C99功能。MinGW的所有软件都可以在64位Windows平台上运行。

ZendStudio 13.5.1 Mac
功能强大的PHP集成开发环境