问题
Can someone explain what is the difference between using mysql_real_escape_string on a string or wrapping `` around the column.
For example "insert into table (``column``) values ('$string')"
or
$escapestring = mysql_real_escape_string($string);
"insert into table (column) values ('$escapedstring')"
What is the difference between these two and what should I use? Thanks.
回答1:
There's a difference between the backtick ` and the single quote '.
The backtick is intended to escape table and field names that may conflict with MySQL reserved words. If I had a field named date and a query like SELECT date FROM mytable I'd need to escape the use of date so that when MySQL parses the query, it will interpret my use of date as a field rather than the datatype date.
The single quote ' is intended for literal values, as in SELECT * FROM mytable WHERE somefield='somevalue'. If somevalue itself contains single quotes, then they need to be escaped to prevent premature closing of the quote literal.
回答2:
Those two aren't related at all (as far I know anyway)
From the manual : http://php.net/manual/en/function.mysql-real-escape-string.php
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().
So essentially what it does is, it will escape characters that are unsafe to go into mysql queries (that might break or malform the query)
So o'reily will become o\'reily
来源：https://stackoverflow.com/questions/5840230/how-to-properly-escape-a-string-via-php-and-mysql