ค้นหาข้อมูลจากฐานข้อมูลด้วย select tag แล้วเลือกที่ All

//ส่งค่าเป็น all มาเลย
if($_POST[type]=='all'){
 $sql="select * from table where type='animal' or type='tree'";
 //หรือแบบนี้ก็ได้
  $sql="select * from table";  // select จากทุก type

}else{
  $sql="select * from table where type='$_POST[type]'";
}

<select name='op'>
<option value='all'>All</option>
<option value='animal'>Animal</option>
<option value='tree'>tree</option>
</select>

if($_POST['op'] == 'animal'){
  $sql = "select * from tb_name where type = 'animal'";
}else if($_POST['select'] == 'tree'){
  $sql = "select * from tb_name where type= 'tree'";
}else{
  $sql = "select * from tb_name";
}
$query=mysql_query($sql);

if($_POST[type]) 
{

$type = $_POST["type"];
$color = $_POST["color"];
if($type=="animal") { $query_where ="WHERE type ='animal' AND color ='$color' ";}  //animal
if($type=="tree"){ $query_where ="WHERE type ='tree' AND color ='$color' ";} //tree
if($type=="all") { $query_where ="";} //all

$sql="select * from table $query_where ";
$query=mysql_query($sql);

}

$sql="SELET * FROM `table`";
if(isset($_POST['type']) && $_POST['type']!=='all') {
     $sql = sprintf(
                 "%s WHERE `type` ='%s' AND `color` ='%s'",
                  $sql,
                  (function_exists('mysql_real_escape_string')?mysql_real_escape_string($_POST['type']):mysql_escape_string($_POST['type'])),
                  (function_exists('mysql_real_escape_string')?mysql_real_escape_string($_POST['color']):mysql_escape_string($_POST['color']))
                );
}
$query=mysql_query($sql);