An '''RdbRelVar''' are variables that take on RdbRelation''''''s as their values.  

Why is the distinction between an RdbRelVar and an RdbRelation important?

''The former contains a relation, the latter is a relation.  Relations are immutable and do not change.  Therefore, state change in a RelationalDatabase is represented by changing the value of a relation variable, or relvar for short.  The answer to the question might be better understood in terms of another question:  Why is the distinction between an integer variable and an integer important?''  -- DaveVoorhis
 
Thanks for the crystal clear explanation and illustration! --BrandonCsSanders

''"replace, don't change" is kind of a functional viewpoint of things (FunctionalProgramming).''
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EditHint: Merge with RelVar and RelationalVariable.