code: public static void appendColumns(StringBuilder s, String[] columns,
  			String[] columnsAs) {
  		String[] wrappedColumns = CoreSQLUtils.quoteWrap(columns);
  		wrappedColumns = CoreSQLUtils.buildColumnsAs(wrappedColumns, columnsAs);
  
  		for (int i = 0; i < wrappedColumns.length; i++) {
  			String column = wrappedColumns[i];
  
  			if (column != null) {
  				if (i > 0) {
  					s.append(", ");
  				}
  				s.append(column);
  			}
  		}
  		s.append(' ');
  	}
docs: Add the names that are non-null in columns to s, separating them with
  commas.
  
  @param s string builder
  @param columns columns
  @param columnsAs columns as