I really think you should use objects for this, but this will work anyway:
import tables var books = newTable[string, TableRef[string, string]]() books["one"] = newTable[string, string]() books["one"]["price"] = "150" echo books["one"]["price"] Run
import tables var books = newTable[string, TableRef[string, string]]() books["one"] = newTable[string, string]() books["one"]["price"] = "150" echo books["one"]["price"]