Newb: convert contents of sql text field to an array or hash

Hi I have a text field in my sql called: keywords
in it are various keywords (suprise!) ‘keywords_1keyword_2keyword_3’
etc.
all keyword phrases take_this_format seperated by an asterisk*

In my rails app I would like to populate checkboxes with my keywords to
show that they are already chosen.

can someone please point me in the right direction?
cheers

Peter