In a way it seems like it.
UNQL was an initiative in 2011 from Couchbase and Sqlite but it never came to an implementation.
http://www.couchbase.com/press-releases/unql-query-language
N1QL targets the same problem. From the website:
N1QL is the first query language to leverage the complete flexibility of JSON with the full power of SQL. Created for use with Couchbase Server, N1QL provides a common query language and JSON-based data model for distributed document-oriented databases.
