Aheo asks if it is ok to have a table with just one column. How about one with no columns, or, given that this seems difficult to do in most modern “relational” DBMSes, a relation with no attributes?
Share
Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
Aheo asks if it is ok to have a table with just one column. How about one with no columns, or, given that this seems difficult to do in most modern “relational” DBMSes, a relation with no attributes?
DEE and cartesian product form a monoid. In practice, if you have Date’s relational summarize operator, you’d use DEE as your grouping relation to obtain grand-totals. There are many other examples where DEE is practically useful, e.g. in a functional setting with a binary join operator you’d get n-ary join = foldr join dee