$txt_search = $_POST['txt_search'];
$txt_search = $_POST['txt_search2'];
$sql_show.=" where properties.properties_id = trick.properties_properties_id
and trick.herb_herb_id = herb.herb_id and properties.properties_name like '%$txt_search%'";
เป็น
$txt_search = $_POST['txt_search'];
$txt_search2 = $_POST['txt_search2'];
$sql_show.=" where properties.properties_id = trick.properties_properties_id
and trick.herb_herb_id = herb.herb_id and (properties.properties_name like '%$txt_search%' or properties.properties_name like '%$txt_search2%')";