Relational Variable

A variable of type "relation", where a "relation" is as defined in the RelationalModel. Relations can be "base relations" (a set of records), or "views" (relations computed based on other relations/RelationalVariables via the RelationalAlgebra or RelationalCalculus).

Relations themselves are immutable. A RelationalVariable, on the other hand, is mutable, and can refer to one relation at one particular instance in time, then another relation at a later time; much as an integer variable can assume different integer values at different moments in time. (The integer "5" is immutable; a variable "x" that refers to 5 now and 3 later, is not.)

Often called relvar for short.

EditHint: merge with RdbRelVar and RelVar