PHP & MYSQL: How can i neglect empty variables from select - php

Question

if i have 4 variables and i want to select DISTINCT values form data base
<?php
$var1 = ""; //this variable can be blank
$var2 = ""; //this variable can be blank
$var3 = ""; //this variable can be blank
$var4 = ""; //this variable can be blank
$result = mysql_query("SELECT DISTINCT title,description FROM table WHERE **keywords ='$var1' OR author='$var2' OR date='$var3' OR forums='$var4'** ");
?>
note: some or all variables ($var1,$var2,$var3,$var4) can be empty
what i want:
i want to neglect empty fields
lets say that $var1 (keywords) is empty it will select all empty fileds, but i want if $var1 is empty the result will be like
$result = mysql_query("SELECT DISTINCT title,description FROM table WHERE author='$var2' OR date='$var3' OR forums='$var4' ");
if $var2 is empty the result will be like
$result = mysql_query("SELECT DISTINCT title,description FROM table WHERE keywords ='$var1' OR date='$var3' OR forums='$var4' ");
if $var1 and $var2 are empty the result will be like
$result = mysql_query("SELECT DISTINCT title,description FROM table WHERE date='$var3' OR forums='$var4' ");
and so on

Answer 1

Try this.
$vars = array(
'keywords' => '', // instead of var1
'author' => '', // instead of var2
'date' => '', // instead of var3
'forums' => '', // instead of var4
);
$where = array();
foreach ($vars as $varname => $varvalue) {
if (trim($varvalue) != '') $where[] = "`$varname` = '" . mysql_real_escape_string($varvalue) . "'";
}
$result = mysql_query("SELECT DISTINCT title, description FROM table WHERE " . join(" OR ", $where));

Answer 2

Thanks alot every one specially experimentX .. Your answer helped me to get the right function i Just replaced (isset) with (!empty) .. Then every thing will be more than OK
$vars = array(
(!empty($_GET["var1"]))? " keyword = '". $_GET["var1"] ."' ": null,
(!empty($_GET["var2"]))? " author = '". $_GET["var2"] ."' ": null,
(!empty($_GET["var3"]))? " date = '". $_GET["var3"] ."' ": null,
(!empty($_GET["var4"]))? " forums = '". $_GET["var4"] ."' ": null
);
function myfilterarray($var)
{
return !empty($var)?$var: null;
}
$newvars = array_filter($vars, 'myfilterarray');
$where = join(" OR ", $newvars);
$sql = "SELECT DISTINCT title, description FROM table ".(($where)?"WHERE ".$where: null);
echo $sql;
with this function if there is empty variable it will be neglected
Thanks again every one for your helpful suggestion

Answer 3

make your select statement string before you call mysql_query(...) so do something along the lines of this:
$queryString = "Select DISTINCT title, description FROM table WHERE";
if(!empty($var1))
$queryString .= " keywords = $var1";
and so forth for all of your variables. you could also implement a for loop and loop through your $var1 - $var# and check for !empty($var#)

Answer 4

Why do you not simply build a if else structure?
Like
if ($var1!="" && $var2!="" && $var3!="" && $var4!=""){
$result = mysql_query("SELECT DISTINCT title,description FROM table WHERE keywords ='$var1' OR author='$var2' OR date='$var3' OR forums='$var4' ")
} else if ($var2!="" && $var3!="" && $var4!=""){
$result = mysql_query("SELECT DISTINCT title,description FROM table WHERE author='$var2' OR date='$var3' OR forums='$var4' ");
} else if {
...
}

Answer 5

(I just posted the below in his duplicate post, so I'm re-posting the below here)
Forgive me if anything is wrong, it's very late here and I just typed this in notepad on Windows, without an environment to test on. * Use with caution * :)
$vars = array(
'blah1' => '',
'blah2' => '',
'blah3' => '',
);
$sql_statement = "SELECT first, last FROM names WHERE";
$clause = "";
foreach($vars as $k=$v)
{
$k = trim($k);
if(!empty($k))
{
$clause .= " `$k` = '$v' OR";
}
}
$clause = rtrim($clause, "OR");
// $clause should have what you want.

Answer 6

Well, there are manu ways of doing this but the shortest way I have found is creating an array of the following form
$vars = array(
(isset($_GET["var1"]))? " keyword = '". $_GET["var1"] ."' ": null,
(isset($_GET["var2"]))? " author = '". $_GET["var2"] ."' ": null,
(isset($_GET["var3"]))? " date = '". $_GET["var3"] ."' ": null,
(isset($_GET["var4"]))? " forums = '". $_GET["var4"] ."' ": null
);
function myfilterarray($var)
{
return !empty($var)?$var: null;
}
$newvars = array_filter($vars, 'myfilterarray');
$where = join(" OR ", $newvars);
$sql = "SELECT DISTINCT title, description FROM table ".(($where)?"WHERE ".$where: null);
echo $sql;
Your result for http://localhost/?var1=sadfsadf&var2=sadfasdf&var3=asdfasdf
SELECT DISTINCT title, description FROM table WHERE keyword =
'sadfsadf' OR author = 'sadfasdf' OR date = 'asdfasdf'
Your result for http://localhost/?
SELECT DISTINCT title, description FROM table