Allow key can be expression from value in the INSERT INTO default VALUES(key,val)

INSERT INTO default VALUES ("cx::" || name || cid, {"name": "Joe", "cid": "349HDH2", "zip":9823});

At present key need to be constant, we should always evaluate key from value, in case of constant it is is no-op, if expression key can be dynamically generated from value.

Keshav Murthy suggestion