php针对用户查询与判断

<?php
 class user
 {
  var $usertable;
  function get_oneuser($field,$value)
  {
   $field_array=array("id","name");  //查询方式
   if(in_array($field,$field_array))
   {
    $sql="SELECT * FROM `$this->usertable` WHERE $field='$value'";
    $db=new database;
    $res=$db->execute($sql);
    $obj_user=mysql_fetch_object($res);
    return $obj_user;
   }
   else echo "查询方式不对";
  }
  function get_moreusers()
  {
   global $db;
   $argnums=func_num_args();
   $argarr=func_get_args();
   switch($argnums)
   {
    case 0:
     $sql="SELECT * FROM `$this->usertable`";
     break;
    case 2:
     $sql="SELECT * FROM `$this->usertable` WHERE $argarr[0]='$argarr[1]'";
     break;
    case 4:
     $sql="SELECT * FROM `$this->usertable` WHERE $argarr[0]='$argarr[1]' AND $argarr[2]='$argarr[3]'";
     break;
   }
   //$db=new database;
   $res=$this->execute($sql);
   $obj_arr=array();
   while($obj=mysql_fetch_object($res))
   {
    $obj_arr[]=$obj;
   }
   return $obj_arr;
  }
 }
?>