does ci support relational db

[eluser]dsi[/eluser]
hi, i m new to ci and i can't figure out how does ci work with relational db. I mean i have 2 tables in db and 1 table has id of another table's content, how do i get another content using that tables id? i have to use loop to echo the content of the 1st table, so can't use another loop, just confused, if u need db structure i can provide.