// statement pattern; we add a triple to the from clause and require it is not deleted; then we add
// conditions for subject, predicate, object, context depending on whether they are variable or
// constant values
TTriples triple = T_TRIPLES.as(name);
JoinTable j_triple = new JoinTable(triple);
j_triple.addCondition(triple.DELETED.isFalse());
tables.add(triple);
TNodes t_subject = null, t_property = null, t_object = null, t_context = null;