[RESOLVED] Does empty() do anything to the variable?

[Archane]

Hi there, I'm having a bit of a problem here.. See code:

$typ = "Program";
// Check if category is set
if (!empty($typ))
{	
		// Category is set, show only correct articles
	$sql = mysql_query("SELECT * FROM Greenbay_guides WHERE id = '$id' AND typ = '$typ'");

}
else
{
	// No category is set, show all
	$sql = mysql_query("SELECT * FROM Greenbay_guides WHERE id = '$id'");
}

echo $typ;

I set $typ to a firm and nice value, "Program" in this case (this is a testcategory). I then check if it's empty or not via empty(), and try to show only the articles i want from my database.
However, somewhere $typ "dissappears", the echo in the bottom proves this, since nothing is echo:ed.

Can someone please explain this to me?

//Thanks, Archane

[scrupul0us]

no, it merely checks to see if a variable is empty... returns boolean TRUE or FALSE

its not entirely clear to me since you didnt wrap your code in PHP tags, but turn on all errors to see if you are having a problem somewhere that is simply white-paging the script

also, I never just echo a var to debug, i always put something before it:

echo 'typ = '.$typ;

that way if you see NOTHING at all, you know your script has errors

[bradgrafelman]

Is display_errors set to On and error_reporting set to E_ALL? It can also be helpful to use [man]var_dump/man since it provides information about a variable (especially helpful as it displays the world NULL if a variable is null, rather than outputting nothing).

[Archane]

Hold your thinkers, noticed a thing in my code.. Hold a second please :p

[Archane]

Ok, Ill give you the entire code..

include ("config.php");
$max = 8; //amount of articles per page. change to what you want
$p = $_GET['p'];
if(empty($p))
{
$p = 1;
}
$limits = ($p - 1) * $max; 
//view the news article!
if(isset($_GET['act']) && $_GET['act'] == "view")
{
$id = $_GET['id'];

// Vad är $typ?
$typ = "Program";
// Kollar ifall någon kategori är angiven
if (!empty($typ))
{	
		// Eller så visas endast de med den anginvna kategorin
	$sql = mysql_query("SELECT * FROM Greenbay_guides WHERE id = '$id' AND typ = '$typ'");

}
else
{
	// Om inte, visa alla
	$sql = mysql_query("SELECT * FROM Greenbay_guides WHERE id = '$id'");
}


while($r = mysql_fetch_array($sql))
{
$link = $r['files'];
echo "<div class='guidecontainer' style='margin-bottom:5px;'>";
echo "<div style='float:left;margin-right:10px;'>";
  echo "<a href='Guides/$link'><img src='http://www.pcstodet.se/Greenbay/Images/Upload/" . $r['img'] . "'  width=\"55px\" height=\"55px\" /></div>";
  echo "<div style='float:left;width:550px;margin-top:5px;'><a href=\"Guides/$link\"><p>";
  echo "<strong>" . $r['name'] . "</strong></p><p>" . $r['descript'] . "</p></a></div></div>";
}
}else{
//view all the news articles in rows
if (!empty($typ))
{	
// Eller så visas endast de med den anginvna kategorin
	$sql = mysql_query("SELECT * FROM Greenbay_guides WHERE typ=".$typ." LIMIT ".$limits.",$max") or die(mysql_error());
}
else
{
		// Om inte, visa alla
	$sql = mysql_query("SELECT * FROM Greenbay_guides LIMIT ".$limits.",$max") or die(mysql_error());
}

//the total rows in the table
$totalres = mysql_result(mysql_query("SELECT COUNT(id) AS tot FROM Greenbay_guides"),0);	
//the total number of pages (calculated result), math stuff...
$totalpages = ceil($totalres / $max); 
while($r = mysql_fetch_array($sql))
{
$link = $r['files'];
echo "<div class='guidecontainer' style='margin-bottom:5px;'>";
echo "<div style='float:left;margin-right:10px;'>";
  echo "<a href='Guides/$link'><img src='http://www.pcstodet.se/Greenbay/Images/Upload/" . $r['img'] . "'  width=\"55px\" height=\"55px\" /></div>";
  echo "<div style='float:left;width:550px;margin-top:5px;'><a href=\"Guides/$link\"><p>";
  echo "<strong>" . $r['name'] . "</strong></p><p>" . $r['descript'] . "</p></a></div></div>";
}
echo "<p>Sida: ";
for($i = 1; $i <= $totalpages; $i++){ 
//this is the pagination link
echo "<a href='archive.php?p=$i'>$i</a>&nbsp;";
}
echo "Typ: ".$typ."";
echo "</p>";
}
?>

What I've done is to firstly, use a basic pagination system, and then tried to implement a categoryfunction to it. Language on most of the //messages is Swedish if you're confused about it.

[scrupul0us]

...and that produces what? any errors? is the echo debug working?

[Archane]

Sorry, no that doesn't give me what i want, every article in the database is still shown, no matter which category i submit. The echo debug returns blank...

See the code in action here: http://www.pcstodet.se/Greenbay/archive.php

Using a MySQL database, these 2 articles are the only ones in there atm.

[scrupul0us]

for starters lets get this in PHP tags and indent it properly.. also taken the liberty to remove the !empty() checks and use isset() which is preferred

<?php
include ("config.php");
$max = 8; //amount of articles per page. change to what you want

$p = $_GET['p'];
if(!isset($p) or !ctype_num($p))
{
	$p = 1;
}
$limits = ($p - 1) * $max;

//view the news article!
if(isset($_GET['act']) && $_GET['act'] == "view")
{
	$id = $_GET['id'];

// Vad är $typ?
$typ = "Program";
// Kollar ifall någon kategori är angiven
if (isset($typ))
{    
	// Eller så visas endast de med den anginvna kategorin
	$sql = mysql_query("SELECT * FROM Greenbay_guides WHERE id = '$id' AND typ = '$typ'");
}
else
{
	// Om inte, visa alla
	$sql = mysql_query("SELECT * FROM Greenbay_guides WHERE id = '$id'");
}

while($r = mysql_fetch_array($sql))
{
	$link = $r['files'];
	echo "<div class='guidecontainer' style='margin-bottom:5px;'>";
	echo "<div style='float:left;margin-right:10px;'>";
	echo "<a href='Guides/$link'><img src='http://www.pcstodet.se/Greenbay/Images/Upload/" . $r['img'] . "'  width=\"55px\" height=\"55px\" /></div>";
	echo "<div style='float:left;width:550px;margin-top:5px;'><a href=\"Guides/$link\"><p>";
	echo "<strong>" . $r['name'] . "</strong></p><p>" . $r['descript'] . "</p></a></div></div>";
}
}
else
{
	//view all the news articles in rows
	if (isset($typ))
	{    

		// Eller så visas endast de med den anginvna kategorin
		$sql = mysql_query("SELECT * FROM Greenbay_guides WHERE typ=".$typ." LIMIT ".$limits.",$max") or die(mysql_error());
	}
	else
	{
		// Om inte, visa alla
		$sql = mysql_query("SELECT * FROM Greenbay_guides LIMIT ".$limits.",$max") or die(mysql_error());
	}

//the total rows in the table
$totalres = mysql_result(mysql_query("SELECT COUNT(id) AS tot FROM Greenbay_guides"),0);    

//the total number of pages (calculated result), math stuff...
$totalpages = ceil($totalres / $max);

while($r = mysql_fetch_array($sql))
{
	$link = $r['files'];
	echo "<div class='guidecontainer' style='margin-bottom:5px;'>";
	echo "<div style='float:left;margin-right:10px;'>";
	echo "<a href='Guides/$link'><img src='http://www.pcstodet.se/Greenbay/Images/Upload/" . $r['img'] . "'  width=\"55px\" height=\"55px\" /></div>";
	echo "<div style='float:left;width:550px;margin-top:5px;'><a href=\"Guides/$link\"><p>";
	echo "<strong>" . $r['name'] . "</strong></p><p>" . $r['descript'] . "</p></a></div></div>";
}
echo "<p>Sida: ";

for($i = 1; $i <= $totalpages; $i++)
{
	//this is the pagination link
	echo "<a href='archive.php?p=$i'>$i</a>&nbsp;";
}

echo "Typ: ".$typ."";
echo "</p>";
}
?>

[scrupul0us]

now in order to get filtered results this condition must be met:

isset($_GET['act']) && $_GET['act'] == "view"

and when i select a radio button option and submit it the only $_GET variable set is 'kat'

[Archane]

changed "act" to "kat", nothing happened. This was there in that pre-made pagination script i found, no idea what it was there for actually. The debug still giving a blank result though..

[Weedpacket]

    $id = $_GET['id']; 

There is nothing in $_GET['id']. Are you sure that's not supposed to be 'kat'? For one thing, 'kat' can never be equal to 'view' - the only options given are "Media", "Utseende", "Photoshop", "Internet" and "Program".

The only other field in the form is the submit button.

[Archane]

Firstly, i removed the $id = $_GET['id']; and in the MySQL query i edited "WHERE id = $id" to "ORDER BY id" (there is a column in the database called id)

and the equal to view thing, i tried to remove this function a while to see what happened, i interpreted it to be the exact same function as the empty() strings.

New code:

<?php
include ("config.php");
$max = 8; //amount of articles per page. change to what you want
$p = $_GET['p'];
if(empty($p))
{
$p = 1;
}
$limits = ($p - 1) * $max; 
//view the news article!
//if(isset($_GET['kat']))
//{

// Vad är $typ?
$typ = "Program";
// Kollar ifall någon kategori är angiven
if (!empty($typ))
{	
		// Eller så visas endast de med den anginvna kategorin
	$sql = mysql_query("SELECT * FROM Greenbay_guides WHERE typ = '$typ' ORDER BY id");

}
else
{
	// Om inte, visa alla
	$sql = mysql_query("SELECT * FROM Greenbay_guides ORDER BY id");
}


while($r = mysql_fetch_array($sql))
{
$link = $r['files'];
echo "<div class='guidecontainer' style='margin-bottom:5px;'>";
echo "<div style='float:left;margin-right:10px;'>";
  echo "<a href='Guides/$link'><img src='http://www.pcstodet.se/Greenbay/Images/Upload/" . $r['img'] . "'  width=\"55px\" height=\"55px\" /></div>";
  echo "<div style='float:left;width:550px;margin-top:5px;'><a href=\"Guides/$link\"><p>";
  echo "<strong>" . $r['name'] . "</strong></p><p>" . $r['descript'] . "</p></a></div></div>";
}
//}else{
//view all the news articles in rows
if (!empty($typ))
{	
// Eller så visas endast de med den anginvna kategorin
	$sql = mysql_query("SELECT * FROM Greenbay_guides WHERE typ = ".$typ." LIMIT ".$limits.",$max") or die(mysql_error());
}
else
{
		// Om inte, visa alla
	$sql = mysql_query("SELECT * FROM Greenbay_guides LIMIT ".$limits.",$max") or die(mysql_error());
}

//the total rows in the table
$totalres = mysql_result(mysql_query("SELECT COUNT(id) AS tot FROM Greenbay_guides"),0);	
//the total number of pages (calculated result), math stuff...
$totalpages = ceil($totalres / $max); 
while($r = mysql_fetch_array($sql))
{
$link = $r['files'];
echo "<div class='guidecontainer' style='margin-bottom:5px;'>";
echo "<div style='float:left;margin-right:10px;'>";
  echo "<a href='Guides/$link'><img src='http://www.pcstodet.se/Greenbay/Images/Upload/" . $r['img'] . "'  width=\"55px\" height=\"55px\" /></div>";
  echo "<div style='float:left;width:550px;margin-top:5px;'><a href=\"Guides/$link\"><p>";
  echo "<strong>" . $r['name'] . "</strong></p><p>" . $r['descript'] . "</p></a></div></div>";
}
echo "<p>Sida: ";
for($i = 1; $i <= $totalpages; $i++){ 
//this is the pagination link
echo "<a href='archive.php?p=$i'>$i</a>&nbsp;";
}
echo "Typ: ".$typ."";
echo "</p>";
//}
?>

This returns an mysql_error, which states "Unknown column 'Program' in 'where clause'". There is a column named "typ" in my database and the two articles i have in it has this column set to "Program". This i don't understand, shouldn't "typ = whatever" be column = value in column?

EDIT: It's the second mysql_query that returns the error, look at the link to see how far it gets.. http://www.pcstodet.se/Greenbay/archive.php

[bradgrafelman]

In the SQL query under the if (!empty($typ)) block, the value for the typ column isn't surrounded in quotes (as all strings must be).

Also note that once typ is dynamically set to user-based input that its value needs to be properly escaped to prevent SQL injection.

[Archane]

What do you mean by a proper escape? As in ".$var." ?

[scrupul0us]

hes saying you need to validate it

if(isset($_GET['typ']) and ctype_alpha($_GET['typ']))
{
//typ is safe and alpha characters only
$typ = $_GET['typ'];
}
else
{
$typ = 'Program';
}

otherwise people can hack your website by placing unscrupulous (no pun intended) code in your query strings to override the DB queries (NEVER put $POST and $GET variables directly into a SQL statement without cleaning/validating the data)

[bradgrafelman]

You could validate it or escape the input, such as by using [man]mysql_real_escape_string/man. Either way, no user-supplied data (e.g. data coming form $GET, $POST, $_COOKIE, and others) should be placed directly into a SQL query without going through one of the two methods.

You still also forgot to include the single quotes around the value inside the string (as a model, look at the first SQL query in the program).

[Archane]

Following code gives this mysql error: "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''0', '8'' at line 1"

<?php
include ("config.php");
$max = 8; //amount of articles per page. change to what you want
$p = $_GET['p'];
if(empty($p))
{
$p = 1;
}
$limits = ($p - 1) * $max; 
//view the news article!
//if(isset($_GET['kat']))
//{

// Vad är $typ?
$typ = "Program";
// Kollar ifall någon kategori är angiven
if (!empty($typ))
{	
		// Eller så visas endast de med den anginvna kategorin
	$sql = mysql_query("SELECT * FROM Greenbay_guides WHERE typ = '$typ' ORDER BY id");

}
else
{
	// Om inte, visa alla
	$sql = mysql_query("SELECT * FROM Greenbay_guides ORDER BY id");
}


while($r = mysql_fetch_array($sql))
{
$link = $r['files'];
echo "<div class='guidecontainer' style='margin-bottom:5px;'>";
echo "<div style='float:left;margin-right:10px;'>";
  echo "<a href='Guides/$link'><img src='http://www.pcstodet.se/Greenbay/Images/Upload/" . $r['img'] . "'  width=\"55px\" height=\"55px\" /></div>";
  echo "<div style='float:left;width:550px;margin-top:5px;'><a href=\"Guides/$link\"><p>";
  echo "<strong>" . $r['name'] . "</strong></p><p>" . $r['descript'] . "</p></a></div></div>";
}
//}else{
//view all the news articles in rows
if (!empty($typ))
{	
// Eller så visas endast de med den anginvna kategorin

$sql = mysql_query("SELECT * FROM Greenbay_guides WHERE typ = '$typ' LIMIT '$limits', '$max'") or die(mysql_error()); //123456789here
}
else
{
		// Om inte, visa alla
	$sql = mysql_query("SELECT * FROM Greenbay_guides LIMIT '$limits', '$max'") or die(mysql_error());
}

//the total rows in the table
$totalres = mysql_result(mysql_query("SELECT COUNT(id) AS tot FROM Greenbay_guides"),0);	
//the total number of pages (calculated result), math stuff...
$totalpages = ceil($totalres / $max); 
while($r = mysql_fetch_array($sql))
{
$link = $r['files'];
echo "<div class='guidecontainer' style='margin-bottom:5px;'>";
echo "<div style='float:left;margin-right:10px;'>";
  echo "<a href='Guides/$link'><img src='http://www.pcstodet.se/Greenbay/Images/Upload/" . $r['img'] . "'  width=\"55px\" height=\"55px\" /></div>";
  echo "<div style='float:left;width:550px;margin-top:5px;'><a href=\"Guides/$link\"><p>";
  echo "<strong>" . $r['name'] . "</strong></p><p>" . $r['descript'] . "</p></a></div></div>";
}
echo "<p>Sida: ";
for($i = 1; $i <= $totalpages; $i++){ 
//this is the pagination link
echo "<a href='archive.php?p=$i'>$i</a>&nbsp;";
}
echo "Typ: ".$typ."";
echo "</p>";
//}
?>

Pretty sure the problem lies at the //123456789here -line, echoing before this line works, after does not.

[scrupul0us]

echo your sql statements and post them

[Archane]

Did not quite understand what u asked for there, the name of the tables in my mysql database or what? :s

[bradgrafelman]

No, echo the SQL queries itself in the error message, something like or die("Query: $sql<br>Error: " . mysql_error()) is a good start.

Also, before that, try removing the quotes around the numerical values after LIMIT, since numerical values are not strings and thus should not be quoted.