Method Any() is the equivalent of exists in the sql. It is used as following.
var query = (from pd in db.TableX
where (from mm in db.TableY where mm.VersionNUmber > 0).Any()
select pd);
or
var query = (from pd in db.TableX
where db.TableY.Any( mm => mm.VersionNUmber > 0 )
select pd);