Eliminating null variables from queries

[Anon]

Lets say I have a form which sends 5 variables to the following php script. If some fields are left as blank and not filled in is there a way to catch these null variables and eliminate before the query takes place? I tried fiddling with is_null() but the only idea i could come up with was a huge series of if statements to catch every null possibility.

Thanks for your time!

<?php

mysql_connect ($host, $user, $pass);
$result = mysql_db_query ("$dbvar","SELECT * FROM articles WHERE articlename = '$articlename' && articlenum = '$articlenum' && date = '$date' && partnum = '$partnum' && model = '$model'");
$rowcount = mysql_num_rows($result);

if ($rowcount >= 1)
{
while ($row = mysql_fetch_array ($result))
{
print $row[articlename];
print $row[summary];
}
}

else
{
echo No records matching your information were found;
}

mysql_free_result ($result);

?>

[Anon]

You could read the search fields into an array and loop through it, building your query from that.

$query = '';

foreach($input as $key => $value) {
if(!empty($input[$key])) {
$query .= "AND $key = $value";
}
}

Of course, you'll have to handle where to put the 'AND' and commas and whatnot.

[Anon]

Thanks for the response, I have tried using what you suggested but i belive i may be missing something or messed up a piece of it because the query does not seem to work. Heres what i did....

$query = '';

foreach($articlename && $articlenum && $date && $partnum && $model as $key => $value)
{
if(!empty($input[$key]))
{
$query .= "AND $key = $value";
}
}

mysql_connect (host,user,pass);
$result = mysql_db_query ("db","SELECT * FROM articles WHERE $query");

[theslinky]

I believe you are missing two things:

1) quotes around your value. Are they all integers? Even if they are, a quote wouldn't hurt you (nor the query) :

$query .= "AND $key = '$value'";

2) Your query will have an extra AND right after the WHERE:

... FROM articles WHERE AND key = 'value', etc...

so you need to ONLY add the "AND" if it's NOT the first key/value pair:

$firstclause = true;

foreach($articlename && $articlenum && $date && $partnum && $model as $key => $value)
{
if(!$firstclause) {
$query .= "AND ";
}
else {
$firstclause = false;
}
if(!empty($input[$key]))
{
$query .= "$key = '$value'";
}
}

hope it works out!

-sridhar

[lanbor]

it works !!

[Anon]

Hmmm well I belive I understand what the foreach loop is doing and it seems to me like it should work, however i have been trying everything i can think of and foreach ALWAYS returns this error

foreach($articlename && $articlenum && $date && $partnum && $model as $key => $value)

Warning: Invalid argument supplied for foreach()

ahhhh, well anyway ill keep experimenting, thanks again for the help!!!