Re: return multiple rows from sql statement
- From: Jerry Stuckle <jstucklex@xxxxxxxxxxxxx>
- Date: Fri, 31 Aug 2007 18:04:21 -0400
The Natural Philosopher wrote:
ELINTPimp wrote:On Aug 31, 2:18 pm, giloosh <giloos...@xxxxxxxxx> wrote:On Aug 30, 9:11 am, Jan Thomä <k...@xxxxxxxxxxxxxx> wrote:
Jerry Stuckle wrote:thanks for the feedback...Jan Thomä wrote:Thanks for the input, and yes I agree, you should definitely cleanse yourI always use the placeholder notation for doing SQL. Concatening SQLNot if you properly cleanse your input. Ensure numeric values are
strings from input values is almost certainly a safe path to SQL
injection.
really numeric, and string values are processed through
mysql_real_escape_string(), for instance.
input before feeding it to the database. My point was simply, that when you
give this kind of work to a framework and always use the ? notation, you
are safe from injection, even if you forget to check a single input
variable (which surely happens from time to time). Also you don't have to
do the conversions to different formats manually, so you save a bit of time
and effort.
Best regards,
Jan
--
_________________________________________________________________________
insOMnia - We never sleep...http://www.insOMnia-hq.de
isn't is safe to just put quotes around the variable
$id = $_POST['id']
$q = "select * from table1 where id = '$id'";
even if id holds none numeric characters, it's still safe... no?
No. That introduces sql injection and cross site scripting
vulnerabilities. mysql_real_escape_strings, as previously suggested,
will help prevent against this.
Dunno what that means, but since Ive been working all day on this sort of stuff..
1/. $q = "select * from table1 where id = '".$id."'";
is what you want. Note the order of quotes and dots.
2/. On my server - virgin php5 apache2 setup, all POST data gets escaped with backslashes into a format that is completely digestible by MySql. So no special processing is needed before inserting or updating data from $_POST[] derived variables.
mysql_real_escape_string is much safer - it takes into consideration the charset currently in use, for one thing. Also, being a MySQL function, it knows what MySQL needs or uses.
3/. One coding bug showed up interestingly when I had done
$new_id=mysql_insert_id;
instead of
$new_id=mysql_insert_id();
The insert of what surprisinlgly was NOT a syntax error, but a string called "mysql_insert_id" into an integer field resulted in the value zero being put in. (Javascript gives you a NaN response when you try and do maths on a string like (1,000 * 1,000) = Not a Number ;-)).
You would have gotten an E_NOTICE if you had them turned on (which you should have in development).
4/. I did have an issue with redisplaying data that had come from a POST derived form..now normally I update the database, then read the data from the database back into the form: In this case I was testing 'failed to update, re-enter some data' and the backslashed stuff gave me issues with quotes and backslashes.
Basically a variable that might be "Fred Bloggs" became \"Fred Bloggs\" after being POSTED. This went into mysql fine using the sort of query I outlined above. And checking using direct database access showed the data in *there* was in fact "Fred Bloggs"
However if I wanted to reinsert that into e.g. text box as i.e.
value="\"Fred Bloggs\"" it didn't work too well at all. Repeated updates left me with truncated data and/or multiple backlashes
mysql_real_escape_string() solves that problem, also.
The key is as follows - in my particular apache php configs anyway - to do the following.
Any POST data that needs to be inserted into input fields and the like -
goes through this:-
function sanitise($string)
{
$string=stripslashes($string); // remove any backslashes
$string=htmlspecialchars($string); // turn oddities that HTML barfs
// on into ampersand stuff
return $string;
}
You shouldn't be doing this on data going into the database. htmlspecialchars() is a display function. Use it after reading out of the database.
What happens, if for instance, you want to create a report to be printed, say using PHP's CLI? Or even MySQL's CLI.
If it's data derived from MySQL it comes out 'as written' with everything correct BUT that can confuse the browser..broswers don't like <> chars or '", but just running it through htmlspecialchars() is enough to sort THAT all out. Inverted commas and single quotes get the &blah; type treatment, and they display fine, and gets the correct stuff into the POST data when submitting the form - I know cos I sent three hours testing it.
i.e. when I did a view source my input text box had
value="&wahtever;Fred Bloggs&whatever;"
inside it, but that showed up as "Fred Bloggs" IN the box, and POSTed up correctly as \"Fred Bloggs\" and went into SQL as "Fred Bloggs"
So the correct php to generate THAT fragment would be
echo ("value=\"".htmlspecialcars($my_value)."\"");
And bugger., Ive just noted that the hardlinked copies of my library - one and the same file - have been busted into two different ones by my editor. It must be one of those that does a 'create tmp file, write it, unlink original, rename temp to original' that I so much hate... The quickest way to break SUNOS4 linked config files was to use EMACS to edit them..
man diff..;-)
}
--
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@xxxxxxxxxxxxx
==================
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