my $column = ( $type eq 'alpha' ) ? 'name' : "CONCAT_WS(' ',keywords,category)";

my $query = "SELECT name, address, city, phone FROM valley ".
    "WHERE $column LIKE ? ORDER BY name LIMIT ?,?";
             
my $sth = $dbh->prepare( $query );
$sth->execute( "%$search%", $start-1, $per_page+1 );

my $table_ref = $sth->fetchall_arrayref;

# here is where/how you check whether anything was returned:

if ( ref( $table_ref ) ne 'ARRAY' or @$table_ref == 0 ) {
    ...
}