求一个图片上传数据库的代码

<form action="" method="post" enctype="multipart/form-data" name="form1" id="form1">
  <input type="file" name="file" />
  <input name="submit" type="submit" id="submit" value="提交" />
</form>

if(isset($_POST['submit'])){
  $file=$_FILES['file'];
  $sql="insert into `表名`(字段名) values('$file')";
 $res=mysql_query($sql);
}