DELETE problem with MySQL

[Gustaf Liljegren]

I've been learning using PHP and MySQL from the tutorial at
freewebmasterhe lp.com. Everything works fine, except deleting things.
The script is invoked with a URL like this:

http://www.example.org/test/delete_entry.php?id=35

And here's the script:

<?
include("dbinfo .inc.php");

$id = $_POST['id'];
mysql_connect($ server, $user, $password);
$query = "DELETE FROM test1 WHERE id = '$id'";
@mysql_select_d b($database) or die("Unable to select database.");
mysql_query($qu ery);
mysql_close();

header("Locatio n: entries.php");
?>

The dbinfo.inc.php file defines the variables $server, $database, $user
and $password. The login part works.

Gustaf

[Noel Wood]

Re: DELETE problem with MySQL

I'm no expert but if the code is invoked via the url then you will need to
use the $_GET global variable to access it not the $_POST one you presently
are using Hope this helps
Noel.

"Gustaf Liljegren" <gustafl@algone t.se> wrote in message
news:cfk825$mfs $1@green.tninet .se...[color=blue]
> I've been learning using PHP and MySQL from the tutorial at
> freewebmasterhe lp.com. Everything works fine, except deleting things.
> The script is invoked with a URL like this:
>
> http://www.example.org/test/delete_entry.php?id=35
>
> And here's the script:
>
> <?
> include("dbinfo .inc.php");
>
> $id = $_POST['id'];
> mysql_connect($ server, $user, $password);
> $query = "DELETE FROM test1 WHERE id = '$id'";
> @mysql_select_d b($database) or die("Unable to select database.");
> mysql_query($qu ery);
> mysql_close();
>
> header("Locatio n: entries.php");
> ?>
>
> The dbinfo.inc.php file defines the variables $server, $database, $user
> and $password. The login part works.
>
> Gustaf[/color]

[Marian Heddesheimer]

Re: DELETE problem with MySQL

On Sat, 14 Aug 2004 07:29:13 +0200, Gustaf Liljegren wrote:
[color=blue]
>freewebmasterh elp.com. Everything works fine, except deleting things.[/color]

often it helps to print out the error message from the database
server. In your case put the line:
echo mysql_error()

after the line:
mysql_query($qu ery)

so you will get a hint what causes the problem. If that don't help,
just print out the query line with "echo $query" to check if you pass
the correct SQL syntax and if you put in all the information that you
wanted to pass to mySQL.

These two things helped me most of the time to find any error related
to mySQL problems.

Regards

Marian

--
Tipps und Tricks zu PHP, Coaching und Projektbetreuun g

http://www.heddesheimer.de/coaching/

[CJ Llewellyn]

Re: DELETE problem with MySQL

"Gustaf Liljegren" <gustafl@algone t.se> wrote in message
news:cfk825$mfs $1@green.tninet .se...[color=blue]
> I've been learning using PHP and MySQL from the tutorial at
> freewebmasterhe lp.com. Everything works fine, except deleting things.
> The script is invoked with a URL like this:
>
> http://www.example.org/test/delete_entry.php?id=35
>
> And here's the script:
>
> <?
> include("dbinfo .inc.php");
>
> $id = $_POST['id'];
> mysql_connect($ server, $user, $password);
> $query = "DELETE FROM test1 WHERE id = '$id'";
> @mysql_select_d b($database) or die("Unable to select database.");
> mysql_query($qu ery);
> mysql_close();
>
> header("Locatio n: entries.php");
> ?>[/color]

If the examples are anything like this then I suggest that you look
elsewhere for free tutorials. Only one statement in the above code attempts
to detect and handle errors (and not very nicely at that), no wonder you are
having trouble.

<?php

include("dbinfo .inc.php");

$id = $_POST['id'];
if($conn = mysql_connect($ server, $user, $password))
{
if(! mysql_select_db ($database))
{
echo "Unable to select the database";
exit;
}
$query = "DELETE FROM test1 WHERE id = '$id'";
$result = mysql_query($qu ery , $conn);
if(! $result || mysql_error($co nn))
{
printf("Unable to delete record: %s [%s]" , mysql_error($co nn) ,
$query);
exit;
}
mysql_close();
header("Locatio n: entries.php");
exit;
}
echo "Unable to open database connection";
?>

This should point out what the error is.

[Chris Hope]

Re: DELETE problem with MySQL

CJ Llewellyn wrote:
[color=blue]
> "Gustaf Liljegren" <gustafl@algone t.se> wrote in message
> news:cfk825$mfs $1@green.tninet .se...[color=green]
>> I've been learning using PHP and MySQL from the tutorial at
>> freewebmasterhe lp.com. Everything works fine, except deleting things.
>> The script is invoked with a URL like this:
>>
>> http://www.example.org/test/delete_entry.php?id=35
>>
>> And here's the script:
>>
>> <?
>> include("dbinfo .inc.php");
>>
>> $id = $_POST['id'];
>> mysql_connect($ server, $user, $password);
>> $query = "DELETE FROM test1 WHERE id = '$id'";
>> @mysql_select_d b($database) or die("Unable to select database.");
>> mysql_query($qu ery);
>> mysql_close();
>>
>> header("Locatio n: entries.php");
>> ?>[/color]
>
> If the examples are anything like this then I suggest that you look
> elsewhere for free tutorials. Only one statement in the above code
> attempts to detect and handle errors (and not very nicely at that), no
> wonder you are having trouble.
>
> <?php
>
> include("dbinfo .inc.php");
>
> $id = $_POST['id'];
> if($conn = mysql_connect($ server, $user, $password))
> {
> if(! mysql_select_db ($database))
> {
> echo "Unable to select the database";
> exit;
> }
> $query = "DELETE FROM test1 WHERE id = '$id'";
> $result = mysql_query($qu ery , $conn);
> if(! $result || mysql_error($co nn))
> {
> printf("Unable to delete record: %s [%s]" , mysql_error($co nn)
> ,
> $query);
> exit;
> }
> mysql_close();
> header("Locatio n: entries.php");
> exit;
> }
> echo "Unable to open database connection";
> ?>
>
> This should point out what the error is.[/color]

Also your code is subject to SQL injection. (Do a Google search if you don't
know what that is http://www.google.com/search?q=sql+injection)

You should cast the $id as an integer like in the following examples:
$id = (int)$_POST['id'];
$id = (int)$_GET['id'];
$id = (int)$_COOKIE['id'];

If it's a string then you need to escape quotes. This can be done by using
the addslashes() function eg:
$string = addslashes($_PO ST['string']);

--
Chris Hope - The Electric Toolbox - http://www.electrictoolbox.com/

[Gustaf Liljegren]

Re: DELETE problem with MySQL

Noel Wood wrote:
[color=blue]
> I'm no expert but if the code is invoked via the url then you will need to
> use the $_GET global variable to access it not the $_POST one you presently
> are using Hope this helps[/color]

This makes sense, and it solves my problem. But I'm still a bit
confused, because in the script for updating entries (included below),
which is also invoked vith a URL, I'm also using POST to fetch the ID,
and it works.

When I use POST in the delete script, I get no error at all, not even
with the line

echo mysql_error();

or all the nice error code CJ Llewellyn provided. I take it as if GET is
right here, but can anyone explain why POST works in the update script?

<?
include("dbinfo .inc.php");

$id = $_POST['id'];
$dt_created = $_POST['dt_created'];
$dt_updated = strftime('%Y-%m-%d %H:%M:%S', time());
$title = $_POST['title'];
$content = $_POST['content'];
$status = $_POST['status'];

mysql_connect($ server, $user, $password);
$query = "UPDATE test1 SET dt_created = '$dt_created', dt_updated =
'$dt_updated', title = '$title', content = '$content', status =
'$status' WHERE id = '$id'";
@mysql_select_d b($database) or die("Unable to select database.");
mysql_query($qu ery);
mysql_close();

// Back to the entries page
header("Locatio n: entries.php");
?>

I'll make it proof to SQL injection too. Thanks.

Gustaf

[Westcoast Sheri]

Re: DELETE problem with MySQL

CJ Llewellyn wrote:
[color=blue]
> "Gustaf Liljegren" <gustafl@algone t.se> wrote in message
> news:cfk825$mfs $1@green.tninet .se...[color=green]
> > I've been learning using PHP and MySQL from the tutorial at
> > freewebmasterhe lp.com. Everything works fine, except deleting things.
> > The script is invoked with a URL like this:
> >
> > http://www.example.org/test/delete_entry.php?id=35
> >
> > And here's the script:
> >
> > <?
> > include("dbinfo .inc.php");
> >
> > $id = $_POST['id'];
> > mysql_connect($ server, $user, $password);
> > $query = "DELETE FROM test1 WHERE id = '$id'";
> > @mysql_select_d b($database) or die("Unable to select database.");
> > mysql_query($qu ery);
> > mysql_close();
> >
> > header("Locatio n: entries.php");
> > ?>[/color]
>
> If the examples are anything like this then I suggest that you look
> elsewhere for free tutorials. Only one statement in the above code attempts
> to detect and handle errors (and not very nicely at that), no wonder you are
> having trouble.
>
> <?php
>
> include("dbinfo .inc.php");
>
> $id = $_POST['id'];
> if($conn = mysql_connect($ server, $user, $password))
>[/color]

.....um....actu ally, shouldn't you have "==" instead of "=" ???
;-)

[CJ Llewellyn]

Re: DELETE problem with MySQL

"Westcoast Sheri" <sheri_deb88@no spamun8nospam.c om> wrote in message
news:4134D24F.E 0674DA@nospamun 8nospam.com...[color=blue]
> CJ Llewellyn wrote:[/color]
-snip-[color=blue][color=green]
> > <?php
> >
> > include("dbinfo .inc.php");
> >
> > $id = $_POST['id'];
> > if($conn = mysql_connect($ server, $user, $password))
> >[/color]
>
> ....um....actua lly, shouldn't you have "==" instead of "=" ???
> ;-)[/color]

if mysql_connect assigns a value to conn then the condition is true.

;-)

Since $conn doesn't exist before the connect statement, it is unlikely to
ever equal the result of mysql_connect unless the connection fails.

[Westcoast Sheri]

Re: DELETE problem with MySQL

CJ Llewellyn wrote:
[color=blue]
> "Westcoast Sheri" <sheri_deb88@no spamun8nospam.c om> wrote in message
> news:4134D24F.E 0674DA@nospamun 8nospam.com...[color=green]
> > CJ Llewellyn wrote:[/color]
> -snip-[color=green][color=darkred]
> > > <?php
> > >
> > > include("dbinfo .inc.php");
> > >
> > > $id = $_POST['id'];
> > > if($conn = mysql_connect($ server, $user, $password))
> > >[/color]
> >
> > ....um....actua lly, shouldn't you have "==" instead of "=" ???
> > ;-)[/color]
>
> if mysql_connect assigns a value to conn then the condition is true.
>
> ;-)
>
> Since $conn doesn't exist before the connect statement, it is unlikely to
> ever equal the result of mysql_connect unless the connection fails.[/color]

Well...just so I wouldn't "speak to soon" I did a little test. I did this
with a "correct" user, server, and password, and then I did it by using an
incorrect password, etc.:

if($conn = mysql_connect($ server, $user, $password)) {
echo "yes";
}

It echoed "yes" both times.

;-)

[CJ Llewellyn]

Re: DELETE problem with MySQL

"Westcoast Sheri" <sheri_deb88@no spamun8nospam.c om> wrote in message
news:4134E24F.3 D8C2546@nospamu n8nospam.com...[color=blue]
> CJ Llewellyn wrote:
>[color=green]
> > "Westcoast Sheri" <sheri_deb88@no spamun8nospam.c om> wrote in message
> > news:4134D24F.E 0674DA@nospamun 8nospam.com...[color=darkred]
> > > CJ Llewellyn wrote:[/color]
> > -snip-[color=darkred]
> > > > <?php
> > > >
> > > > include("dbinfo .inc.php");
> > > >
> > > > $id = $_POST['id'];
> > > > if($conn = mysql_connect($ server, $user, $password))
> > > >
> > >
> > > ....um....actua lly, shouldn't you have "==" instead of "=" ???
> > > ;-)[/color]
> >
> > if mysql_connect assigns a value to conn then the condition is true.
> >
> > ;-)
> >
> > Since $conn doesn't exist before the connect statement, it is unlikely[/color][/color]
to[color=blue][color=green]
> > ever equal the result of mysql_connect unless the connection fails.[/color]
>
> Well...just so I wouldn't "speak to soon" I did a little test. I did this
> with a "correct" user, server, and password, and then I did it by using an
> incorrect password, etc.:
>
> if($conn = mysql_connect($ server, $user, $password)) {
> echo "yes";
> }
>
> It echoed "yes" both times.[/color]

DOH! Just goes to show you should always test before posting :-)

[Westcoast Sheri]

Re: DELETE problem with MySQL

CJ Llewellyn wrote:
[color=blue]
> "Westcoast Sheri" <sheri_deb88@no spamun8nospam.c om> wrote in message
> news:4134E24F.3 D8C2546@nospamu n8nospam.com...[color=green]
> > CJ Llewellyn wrote:
> >[color=darkred]
> > > "Westcoast Sheri" <sheri_deb88@no spamun8nospam.c om> wrote in message
> > > news:4134D24F.E 0674DA@nospamun 8nospam.com...
> > > > CJ Llewellyn wrote:
> > > -snip-
> > > > > <?php
> > > > >
> > > > > include("dbinfo .inc.php");
> > > > >
> > > > > $id = $_POST['id'];
> > > > > if($conn = mysql_connect($ server, $user, $password))
> > > > >
> > > >
> > > > ....um....actua lly, shouldn't you have "==" instead of "=" ???
> > > > ;-)
> > >
> > > if mysql_connect assigns a value to conn then the condition is true.
> > >
> > > ;-)
> > >
> > > Since $conn doesn't exist before the connect statement, it is unlikely[/color][/color]
> to[color=green][color=darkred]
> > > ever equal the result of mysql_connect unless the connection fails.[/color]
> >
> > Well...just so I wouldn't "speak to soon" I did a little test. I did this
> > with a "correct" user, server, and password, and then I did it by using an
> > incorrect password, etc.:
> >
> > if($conn = mysql_connect($ server, $user, $password)) {
> > echo "yes";
> > }
> >
> > It echoed "yes" both times.[/color]
>
> DOH! Just goes to show you should always test before posting :-)[/color]

Okay....now if you could help on one tiny little problem: I *don't* want php to
display error messages to my browser. I don't have access to server compile
files, so in the past simply placing "error_reportin g(E_NONE);" at the top of
my script worked. Now it doesn't work. What am I doing wrong? Or does that
directive work on some servers but not others???

[Jasper Bryant-Greene]

Re: DELETE problem with MySQL

Westcoast Sheri wrote:
[color=blue]
> Okay....now if you could help on one tiny little problem: I *don't* want php to
> display error messages to my browser. I don't have access to server compile
> files, so in the past simply placing "error_reportin g(E_NONE);" at the top of
> my script worked. Now it doesn't work. What am I doing wrong? Or does that
> directive work on some servers but not others???[/color]

Try:

ini_set('displa y_errors','0');

at the start of your php script.

--
Jasper Bryant-Greene
Cabbage Promotions

[CJ Llewellyn]

Re: DELETE problem with MySQL

"Westcoast Sheri" <sheri_deb88@no spamun8nospam.c om> wrote in message
news:41355414.D 272B7CB@nospamu n8nospam.com...[color=blue]
> CJ Llewellyn wrote:
>[color=green]
> > "Westcoast Sheri" <sheri_deb88@no spamun8nospam.c om> wrote in message
> > news:4134E24F.3 D8C2546@nospamu n8nospam.com...[color=darkred]
> > > CJ Llewellyn wrote:
> > >
> > > > "Westcoast Sheri" <sheri_deb88@no spamun8nospam.c om> wrote in message
> > > > news:4134D24F.E 0674DA@nospamun 8nospam.com...
> > > > > CJ Llewellyn wrote:
> > > > -snip-
> > > > > > <?php
> > > > > >
> > > > > > include("dbinfo .inc.php");
> > > > > >
> > > > > > $id = $_POST['id'];
> > > > > > if($conn = mysql_connect($ server, $user, $password))
> > > > > >
> > > > >
> > > > > ....um....actua lly, shouldn't you have "==" instead of "=" ???
> > > > > ;-)
> > > >
> > > > if mysql_connect assigns a value to conn then the condition is true.
> > > >
> > > > ;-)
> > > >
> > > > Since $conn doesn't exist before the connect statement, it is[/color][/color][/color]
unlikely[color=blue][color=green]
> > to[color=darkred]
> > > > ever equal the result of mysql_connect unless the connection fails.
> > >
> > > Well...just so I wouldn't "speak to soon" I did a little test. I did[/color][/color][/color]
this[color=blue][color=green][color=darkred]
> > > with a "correct" user, server, and password, and then I did it by[/color][/color][/color]
using an[color=blue][color=green][color=darkred]
> > > incorrect password, etc.:
> > >
> > > if($conn = mysql_connect($ server, $user, $password)) {
> > > echo "yes";
> > > }
> > >
> > > It echoed "yes" both times.[/color]
> >
> > DOH! Just goes to show you should always test before posting :-)[/color]
>
> Okay....now if you could help on one tiny little problem: I *don't* want[/color]
php to[color=blue]
> display error messages to my browser. I don't have access to server[/color]
compile[color=blue]
> files, so in the past simply placing "error_reportin g(E_NONE);" at the top[/color]
of[color=blue]
> my script worked. Now it doesn't work. What am I doing wrong? Or does that
> directive work on some servers but not others???
>
>[/color]