select t.table_name tableName,f.comments comments
  from user_tables t
 inner join user_tab_comments f
    on t.table_name = f.table_name

SELECT t.TABLE_NAME  tableName,t.COLUMN_NAME columnName,t.DATA_TYPE   dataType,a.COMMENTS
  FROM USER_TAB_COLUMNS t
  LEFT JOIN USER_COL_COMMENTS a
    ON t.table_name = a.table_NAME
   AND t.COLUMN_NAME = a.COLUMN_NAME