Relational calculus of domains and tuples

Question

Is there a “real” difference between the two above? Besides the minimal difference between their syntax?

Answer 1

A calculus tied to a tuple uses tuple variables, i.e. a variable whose only valid values ​​are tuples of this relation. For example. QUEL. Domain-oriented calculus has domain variables, that is, variables that are located above the underlying domains, and not above the ratio. For example. ILL, DEDUCE .... A calculus tied to a tuple uses tuple variables, i.e. A variable whose only valid values ​​are tuples of this relationship. E

Answer 2

. , . .

Answer 3

, , - , , . , DRA ...

Answer 4

, :

Instead of having a range of variables in tuples, the variables are arranged in separate values ​​from the attribute domains. To form a relation of degree n for the result of the query, we must have n of these domain variables - one for each attribute.