code: void lookupSelectHints(
  		SqlSelect select,
  		SqlParserPos pos,
  		Collection<SqlMoniker> hintList) {
  		IdInfo info = idPositions.get(pos.toString());
  		if ((info == null) || (info.scope == null)) {
  			SqlNode fromNode = select.getFrom();
  			final SqlValidatorScope fromScope = getFromScope(select);
  			lookupFromHints(fromNode, fromScope, pos, hintList);
  		} else {
  			lookupNameCompletionHints(info.scope, info.id.names,
  				info.id.getParserPosition(), hintList);
  		}
  	}
docs: Looks up completion hints for a syntactically correct select SQL that has
  been parsed into an expression tree.
  
  @param select   the Select node of the parsed expression tree
  @param pos      indicates the position in the sql statement we want to get
  completion hints for
  @param hintList list of {@link SqlMoniker} (sql identifiers) that can
  fill in at the indicated position