SELECT T.OWNER
, T.TABLE_NAME
, TC.COMMENTS
, C.COLUMN_NAME
, CC.COMMENTS
, C.DATA_TYPE
, C.DATA_LENGTH
FROM ALL_TABLES T
, ALL_TAB_COMMENTS TC
, ALL_TAB_COLUMNS C
, ALL_COL_COMMENTS CC
WHERE T.TABLE_NAME = TC.TABLE_NAME
AND T.TABLE_NAME = C.TABLE_NAME
AND C.TABLE_NAME = CC.TABLE_NAME
AND C.COLUMN_NAME = CC.COLUMN_NAME
AND T.OWNER IN ('AAAA', 'BBBB')
ORDER BY T.OWNER
, T.TABLE_NAME
, C.COLUMN_ID
;