addslashes vs. mysql_real_escape_string

When I look directly in my db field I see a difference between these two
functions. The top line (seebelow) was inserted with addslashes vs. the
bottom line where I used mysql_real_escape_string. Obviously addslashes
really escapes the apostrophe. But I thought mysql_real_escape_string is
supposed to do that too - can anyone explain? Thanks, Lee G.

This is Aviva\'s website.
This is Sarah's website.

leegold2 wrote:
> When I look directly in my db field I see a difference between these two
> functions. The top line (seebelow) was inserted with addslashes vs. the
> bottom line where I used mysql_real_escape_string. Obviously addslashes
> really escapes the apostrophe. But I thought mysql_real_escape_string is
> supposed to do that too - can anyone explain? Thanks, Lee G.
>
> This is Aviva\'s website.
> This is Sarah's website.

What were:
* the original strings before escaping
* the strings after escaping, as they appeared in the SQL you sent to
the server?

I don't see any difference on a test string with an apostrophe on these
functions in 4.3.8 or 5.0.2:
<?php
$originalstring = "Apostrophe's rock";
echo $originalstring, "\n";
echo addslashes( $originalstring ), "\n";
echo mysql_escape_string( $originalstring ), "\n";
echo mysql_real_escape_string( $originalstring ), "\n";
?>

output:
Apostrophe's rock
Apostrophe\'s rock
Apostrophe\'s rock
Apostrophe\'s rock

Can you confirm that the pre-escaping string for "This is Aviva\'s
website." did not contain a backslash, and that the same query was used
to insert both samples? Did the data from from a literal string, a file,
or from a web form? If you're using the magic_quotes_gpc option
(unfortunately the default is on, I believe), you need to run
stripslashes() on any text that comes from GET/POST/COOKIE variables
before further processing.

-- brion vibber (brion @ pobox.com)