oracle table comment

                                    COMMENT ON COLUMN TABLE_NAME.MY_COLUMN IS 'A column comment';
SELECT * FROM ALL_COL_COMMENTS WHERE TABLE_NAME = 'TABLE_NAME';
-- All schema columns:
SELECT t.OWNER, t.TABLE_NAME, c.COLUMN_NAME, com.COMMENTS
FROM DBA_TABLES t LEFT JOIN DBA_TAB_COLUMNS c
    ON c.OWNER = t.OWNER AND c.TABLE_NAME = t.TABLE_NAME
LEFT JOIN DBA_COL_COMMENTS com ON com.OWNER = c.OWNER AND com.TABLE_NAME = c.TABLE_NAME
    AND com.COLUMN_NAME = c.COLUMN_NAME
WHERE t.OWNER = 'MY_OWNER' AND t.DROPPED = 'NO'
ORDER BY t.OWNER, t.TABLE_NAME, c.COLUMN_NAME;

                                    SELECT * FROM ALL_TAB_COMMENTS WHERE TABLE_NAME = 'MY_TABLE';  -- Table comment
SELECT * FROM ALL_COL_COMMENTS WHERE TABLE_NAME = 'MY_TABLE';  -- Columns comments

-- All owner tables:
SELECT t.OWNER, t.TABLE_NAME, com.COMMENTS
FROM DBA_TABLES t
LEFT JOIN DBA_TAB_COMMENTS com ON com.OWNER = t.OWNER AND com.TABLE_NAME = t.TABLE_NAME
WHERE t.OWNER = 'TRANSFERT_DOAAT' AND t.DROPPED = 'NO'
ORDER BY t.OWNER, t.TABLE_NAME;