PHP implements image upload and compression

<?php
$db_host = '';
$db_user = '';
$db_psw = '';
$db_name = '';
$db_port = '';
$sqlconn=new mysqli($db_host,$db_user,$db_psw,$db_name);
$q="set names utf8;";
$result=$sqlconn->query($q);
if (mysqli_connect_errno()) {
 printf("Connect failed: %s\n", mysqli_connect_error());
 exit();
}
?>

<?php
require ("");
require ("upload_img.php");
$real_img=$uploadfile; 
$small_img=$uploadfile_resize;
$insert_sql = "insert into img (real_img,small_img) values (?,?)";
$result = $sqlconn -> prepare($insert_sql);
$result -> bind_param("ss", $real_img,$small_img);
$result -> execute();
?>

<?php 
//Set the file save directory$uploaddir = "upfiles/"; 
//Set the type that allows uploading of files$type=array("jpg","gif","bmp","jpeg","png"); 

//Get the file suffix name functionfunction fileext($filename) 
{ 
 return substr(strrchr($filename, '.'), 1); 
} 

//Generate random file name functionfunction random($length) 
{ 
 $hash = 'CR-'; 
 $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz'; 
 $max = strlen($chars) - 1; 
 mt_srand((double)microtime() * 1000000); 
 for($i = 0; $i < $length; $i++) 
 { 
  $hash .= $chars[mt_rand(0, $max)]; 
 } 
 return $hash; 
} 

$a=strtolower(fileext($_FILES['filename']['name'])); 

//Judge file typeif(!in_array(strtolower(fileext($_FILES['filename']['name'])),$type)) 
{ 
 $text=implode(",",$type); 
 $ret_code=3;//File type error $page_result=$text;
 $retArray = array('ret_code' => $ret_code,'page_result'=>$page_result);
 $retJson = json_encode($retArray);
 echo $retJson;
 return;
} 

//The file name of the generated target fileelse
{ 
 $filename=explode(".",$_FILES['filename']['name']); 
 do 
 { 
  $filename[0]=random(10); //Set the random number length  $name=implode(".",$filename); 
  //$name1=$name.".Mcncc"; 
  $uploadfile=$uploaddir.$name; 
 } 

 while(file_exists($uploadfile)); 

 if (move_uploaded_file($_FILES['filename']['tmp_name'],$uploadfile)) 
 { 
  if(is_uploaded_file($_FILES['filename']['tmp_name'])) 
  {
   $ret_code=1;//Upload failed  } 
 else 
 {//Upload successfully  $ret_code=0;
 } 
 } 
$retArray = array('ret_code' => $ret_code);
$retJson = json_encode($retArray);
echo $retJson;
}

//Compress the picture
$uploaddir_resize="upfiles_resize/";
$uploadfile_resize=$uploaddir_resize.$name;

//$pic_width_max=120;
//$pic_height_max=90;
//The above and the following comments can be used in combination to make the picture compressed according to the calculated proportions
$file_type=$_FILES["filename"]['type'];

function ResizeImage($uploadfile,$maxwidth,$maxheight,$name)
{
 //Get the current image size $width = imagesx($uploadfile);
 $height = imagesy($uploadfile);
 $i=0.5;
 //The size of the generated thumbnail if(($width > $maxwidth) || ($height > $maxheight))
 {
  /*
  $widthratio = $maxwidth/$width;
  $heightratio = $maxheight/$height;
  
  if($widthratio < $heightratio)
  {
   $ratio = $widthratio;
  }
  else
  {
    $ratio = $heightratio;
  }
  
  $newwidth = $width * $ratio;
  $newheight = $height * $ratio;
  */
  $newwidth = $width * $i;
  $newheight = $height * $i;
  if(function_exists("imagecopyresampled"))
  {
   $uploaddir_resize = imagecreatetruecolor($newwidth, $newheight);
   imagecopyresampled($uploaddir_resize, $uploadfile, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
  }
  else
  {
   $uploaddir_resize = imagecreate($newwidth, $newheight);
   imagecopyresized($uploaddir_resize, $uploadfile, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
  }
  
  ImageJpeg ($uploaddir_resize,$name);
  ImageDestroy ($uploaddir_resize);
 }
 else
 {
  ImageJpeg ($uploadfile,$name);
 }
}



if($_FILES["filename"]['size'])
{
 if($file_type == "image/pjpeg"||$file_type == "image/jpg"|$file_type == "image/jpeg")
 {
  //$im = imagecreatefromjpeg($_FILES[$upload_input_name]['tmp_name']);
  $im = imagecreatefromjpeg($uploadfile);
 }
 elseif($file_type == "image/x-png")
 {
  //$im = imagecreatefrompng($_FILES[$upload_input_name]['tmp_name']);
  $im = imagecreatefromjpeg($uploadfile);
 }
 elseif($file_type == "image/gif")
 {
  //$im = imagecreatefromgif($_FILES[$upload_input_name]['tmp_name']);
  $im = imagecreatefromjpeg($uploadfile);
 }
 else//Default jpg {
  $im = imagecreatefromjpeg($uploadfile);
 }
 if($im)
 {
  ResizeImage($im,$pic_width_max,$pic_height_max,$uploadfile_resize);
 
  ImageDestroy ($im);
 }
} 
?>