How to insert image into Mysql?

[wxdqz]

Could you help me that I tried many times to do like this:

I made a form and want to upload file(gif,ram format) in to mysql table.
How to write the table structrues? the fields type is image?

Thank you!
<?php
if($submit)
{
$db=connect_function();
mysql_query("insert into image (picture) values ('$filename');");
}
//the $filename is the <input type=file name=filename>
?>

there must be something wrong in it.I am eager to know.Thank you again.