Are there some mathematical theories/theorems/... behind modern development of database management systems and in particular of SQL ? I am refreshing my knowledge of these things …

hi, how can division R:S be minimally produced from the basic RA's operators (select,project,union,cartezian,set difference and renaming) on the followed cases: 1. it is known that …

Still wading through higher category theory. I find the subject a bit intimidating, not so much for technical reasons, but because I lack sufficient intuition as to the motivation( …

Can anyone point me to short survey articles of mathmatical expositions of Codd's relational algebra and calculus (from database theory)? I suspect there's some straightforward ca …