php - 链接标识符在 mysql_real_escape_string() 中的重要性

Question

为什么在使用 mysql_real_escape_string() 时需要将链接标识符作为输入。我知道该函数应该与 MySQL 查询一起使用，但该函数实际上只是一个字符串操作。

Answer 1

来自 the PHP manual :

Escapes special characters in the unescaped_string , taking into account the current character set of the connection so that it is safe to place it in a mysql_query(). If binary data is to be inserted, this function must be used.

和:

If the link identifier is not specified, the last link opened by mysql_connect() is assumed. If no such link is found, it will try to create one as if mysql_connect() was called with no arguments. If no connection is found or established, an E_WARNING level error is generated.

需要一个连接来确定字符集。