Which of the following has same expressive power with regard to relational query language?
(a) Relational algebra and domain relational calculus
(b) Relational algebra and tuples relational calculus
(c) Relational algebra and domain relational calculus restricted to safe expression
(d) Relational algebra and tuples relational calculus restricted to safe expression
Pick an option to check yourself, or open the answer below.
Show answer & explanation
Correct answer: B. (c) and (d) only
Explanation
Relational algebra equals tuple and domain relational calculus restricted to safe expressions; unrestricted calculus can express unsafe (infinite) queries.
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