With regards to the expressive power of the formal relational query languages, which of the following statements is true?
SQL is having more power than RA or TRC. Because aggregate , grouping , ordering all these can be done by SQL but can not be done by RA or TRC queries.
RA→ Relational algebra.
TRC→ Tuple relational calculus.
Good examples @raja11sep :)
Relational algebra has the same power as safe relational calculus as:
Option "B" is also correct but option "C" is more appropriate because Relational calculus have some unsafe operations and because of those unsafe operations sometimes it may fall in ∞(infinite) loop.
so relational algebra has the same power as safe relational calculus
A query can be written in safe Relational Calculus if and only if it can be written in Relational Algebra means it can be written in Relational Calculus as well as Relational Algebra, but Relational calculus also have some unsafe operations and because of those unsafe operations sometimes create ∞(infinite) loop.
So we can say that all safe relational calculus query can be translate into relational algebra