Well, no; syntax-case allows arbitrary Scheme, so it is Turing-complete.  SQL is not, unless the implementation of CTEs allows arbitrary nesting.  SQL is also extremely rigid, deficient, and un-orthogonal compared to a true relational algebra implementation like Tutorial D.

See also Linda, in which you broadcast arbitrary tuples (could be trees, too) into Lindaspace and then anyone can query the space with pattern matching, returning the first matching tuple with or without atomically removing it.

America is not a morally pure country. No country ever has been or ever
will be, but in democratic countries you get things done by compromising
your principles in order to form alliances with groups about whom you
have grave doubts.  --Richard Rorty, Achieving Our Country (1998)