Freinds I am stuck.

I have a website where the client is able to search through a database of BOOKS and recommend those books to their clients. I have a search engine set up that allows them to search based on a number of parameters - age of the children, author, so so on.

I have a new field in the database for the Dewey Decimal System. it's a single field, but I would like my client to be able to search based on a RANGE (13.1 - 13.5 and so on)

I have successfully queried the database using just ONE field as follows:

The form:

<input type="text" name="search_data[DEWEY]" value="{$prefilled.DEWEY|escape}" />

The PROCESSOR that fetches the results:

 if($DEWEY) {
  $fieldid = func_query_first_cell("SELECT fieldid FROM $sql_tbl[extra_fields] WHERE service_name='DEWEY'") ;
  if($fieldid) {
   $pids = func_query_column("SELECT productid FROM $sql_tbl[extra_field_values] WHERE fieldid='$fieldid' AND value LIKE '%$DEWEY%'") ;
   if(is_array($pids)) {
    $where[] = "p.productid IN ('" . implode("', '", $pids) . "')" ;
   } else {
    $where[] = "p.productid IN ('')" ; // products not found
   }  }
   }

NOW I would like the client to be able to submit a RANGE of numbers as follows:

<input type="text" name="search_data[DEWEY_from]" value="{$prefilled.DEWEY_from|escape}" size="10" /> - <input type="text" name="search_data[DEWEY_to]" value="{$prefilled.DEWEY_to|escape}" size="10" />

THere are other fields in the search engine that are using ranges, and I have tried to mimic that code but I am getting errors - mainly because there is a different table being queried, but here is an example:

 if($price_from || $price_to) {
  if($price_from) {
   $where[] = "pr.price >= '$price_from'" ;
  }
  if($price_to) {
   $where[] = "pr.price <= '$price_to'" ;
  }
 }

Anything I do to the if($DEWEY) code seems to break the search and not work. Any thoughts about how I can display these results based on this range search?

MANY Thanks