Q:

when i enter only min value then it consider max as zero and return me null data

When I enter only min value then it consider max as zero and return me null data
$min=$_REQUEST['min'];     
$max=$_REQUEST['max'];     
$q3="select * from product where '$min' < `price` < '$max'";    
$q=mysql_query($q3);

A:

Change the query by max value:
$min=$_REQUEST['min'];

$max=$_REQUEST['max'];

if( empty($max) )
   $q3="select * from product where price > '$min'";
else
   $q3="select * from product where price > '$min' and price < '$max' ";

$q=mysql_query($q3);

One more correction you should start using PDO . method your are using is depreciated.
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