translation from Datalog to SQL -

i still thinking on how translate recursivity of datalog program sql, such as

p(x,y) <- q(x,y). q(x,y) <- p(x,z), a(y). 

where a/1 edb predicate. this, there co-dependency between p , q. longer queries, how solve problem?

moreover, there system implement translation? if there is, may know system or paper may refer?

if adopt approach of "tabling" previous conclusions , forward-chain reasoning on these infer new conclusions, no recursive "depth" required.

bear in mind datalog requires restrictions on rules , variable assure finite termination , hence finitely many conclusions. variables must have finite range of possible values, example.

let's assume example refers constants rather variables:

p(x,y) <- q(x,y). q(x,y) <- p(x,z), a(y). 

one wrinkle want a/1 implemented extended stored procedure or external code. propose tabling results of calling a on possible arguments (finitely many). these after among conclusions (provable statements) of system.

once done forward-chaining inference proceeds iteratively rather recursively. @ each step consider each rule, applying premises (right-hand sides) obtained (tabled) conclusions if produces new conclusion. if no rule produces new conclusion in current step, halt. proof procedure complete.

in example proofs stop after a facts adduced, because there no conclusions sufficient apply either rule new conclusions.