UBB6 does not store the markup code.
When you enter a post, it goes through the markup proces, where all UBB is translated to the corresponding HTML.
It only goes through this proces if you post it.
When you edit a post, the HTML is translated back to UBB code.
So there is no way you can add UBB code to a post by editting the table directly. It has to go through some translation/processing code to proces that markup code.