php - Can't set url value for $_GET when linking to another page via <a> tag -

i have login page starts session, sets email , session_id value in loggedin database table. when login successful, goes

dashboard.php?sesid="session_id" 

now when on dashboard page, set $userid session id url value.

i have link:

<a href="?sesid=".$userid."">dashboard</a> 

but when click on it, url says

dashboard.php?sesid= 

why id not popping up?

your link should this:

<a href="?sesid='<?php echo $userid; ?>'>dashboard</a>