Delete from database ONLY if the uid from the database matches the uid in session

My users can create a note that they can later delete, if they wish.

I'm storing the note in the database and these are my columns in my database: id, uid, note, time.

In my model (model_entry), I have this code to delete the note from database

PHP Code:

$this->db->where('pid', $pid);
        $this->db->delete('dayone_entries'); 


This, however, can let anyone delete any post id if they have the post id.

This is what I mean.

My view (view_all_entries):

PHP Code:

<a href="<?php echo base_url() . "profile/delete_entry/" . $data->pid; ?>">Delete</a> 


As you can see, it gets the pid and puts it in the website url and then moves it on to my controller.

My controller (profile.php) :

PHP Code:

function delete_entry() {
        $this->load->model('model_entry');
        $pid = $this->uri->segment(3);
        $this->model_entry->entry_delete($pid);
        $this->entries();
    } 


And finally, my model which I have also written the code for above.

Model (model_entry):

PHP Code:

$this->db->where('pid', $pid);
        $this->db->delete('dayone_entries'); 


My question: I don't want anyone going in and deleting the notes. The person can only delete the note if IT BELONGS TO THEIR UID.

So if the pid is 3 and the uid is 1, only the user which has the uid 3 can delete the note (pid 3), no one else.