问仅上传csv文件并在保存到数据库之前重命名

EN

$org_file_name = $_FILES['file1']['name'];
$file_size = $_FILES['file1']['size'];
$ext = strtolower(pathinfo($org_file_name, PATHINFO_EXTENSION));
$file_path = 'docs/';
$rand = rand(111,999);          
if($ext == 'csv')
{
    if(file_exists($file_path))
    {
         $file_path = 'docs/'.$org_file_name;
    }
    if(!move_uploaded_file($_FILES['file1']['tmp_name'],$file_path))
    {
        die ('<script> alert("file not uploaded successfully."); </script>');
    }           
}
else
{
    die ('<script> alert("Uploaded only CSV files."); </script>');
}