Qrlew: Rewriting SQL into Differentially Private SQL
Nicolas Grislain Paul Roussel Victoria de Sainte Agathe
This paper introduces Qrlew, an open source library that can parse SQL
queries into Relations -- an intermediate representation -- that keeps track of
rich data types, value ranges, and row ownership; so that they can easily be
rewritten into differentially-private equivalent and turned back into SQL
queries for execution in a variety of standard data stores.
  With Qrlew, a data practitioner can express their data queries in standard
SQL; the data owner can run the rewritten query without any technical
integration and with strong privacy guarantees on the output; and the query
rewriting can be operated by a privacy-expert who must be trusted by the owner,
but may belong to a separate organization.