php 安全

如何不使用prepared statment，而是用过滤的方法避免SQL注入呢？
一般来说mysql自带的过滤函数是比较可靠的。mysql_real_escape_string()
但是这个函数在某些字符集中有问题，比如GBK。如果你用UTF8那没关系。
在PHP里设置数据库的字符集不应该用：mysql_query("SET NAMES UTF8");
而应该用：mysql_set_charset()
这样mysql_real_escape_string()在处理GBK编码的时候就不会出问题了。
mysql_real_escape_string() not safe when SET NAMES is used
use mysql_set_charset() instead.
Note: This is the preferred way to change the charset. Using mysql_query() to execute SET NAMES .. is not recommended.
SET NAMES is usually used to switch the encoding from what is default to what the application needs. This is done in a way that mysql_real_escape_string doesn’t know about this. This means if you switch to some multi byte encoding that allows backslash as 2nd 3rd 4th… byte you run into trouble, because mysql_real_escape_string doesn’t escape correctly. UTF-8 is safe…
Safe way to change encoding is mysql_set_charset, but that is only available in new PHP versions