[Koha] Where can I find documentation on the Koha tables

Where can I find where information is stored in the Koha tables? For instance, I know that books are entered via the records-import table and entries end up in the items and biblioitems table. When a book is checked out what tables are changed to show that the book is checked out. If the book is "deleted" from koha, does that release the book from the table which shows that the book is checked out? Any infomation is welcome and thanks to everyone whose helped me with this issue. Phillip