Oracle 21c

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ALTER SESSION SET NLS_DATE_FORMAT = 'YYYY-MM-DD HH24:MI:SS';
CREATE TABLE table_name (
  id    NUMBER(10,0),
  value VARCHAR2(20)
);
COMMENT ON TABLE table_name IS 'A table for testing comments.';
COMMENT ON COLUMN table_name.id IS 'The identifier.';
COMMENT ON COLUMN table_name.value IS 'The value.';
SELECT ut.table_name,
       ut.tablespace_name,
       utc.comments
FROM   user_tables ut
       LEFT OUTER JOIN user_tab_comments utc
       ON ut.table_name = utc.table_name
ORDER BY ut.table_name


TABLE_NAME
TABLESPACE_NAME
COMMENTS


TABLE_NAME
USERS
A table for testing comments.


SELECT utc.table_name,
       utc.column_name,
       utc.data_type,
       utc.data_length,
       utc.data_precision,
       utc.data_scale,
       utc.data_default,
       ucc.comments
FROM   user_tab_columns utc
       LEFT OUTER JOIN user_col_comments ucc
       ON utc.table_name = ucc.table_name AND utc.column_name = ucc.column_name
ORDER BY utc.table_name, utc.column_name, utc.column_id


TABLE_NAME
COLUMN_NAME
DATA_TYPE
DATA_LENGTH
DATA_PRECISION
DATA_SCALE
DATA_DEFAULT
COMMENTS


TABLE_NAME
ID
NUMBER
22
10
0
null
The identifier.

TABLE_NAME
VALUE
VARCHAR2
20
null
null
null
The value.

TABLE_NAME	COLUMN_NAME	DATA_TYPE	DATA_LENGTH	DATA_PRECISION	DATA_SCALE	DATA_DEFAULT	COMMENTS
TABLE_NAME	ID	NUMBER	22	10	0	null	The identifier.
TABLE_NAME	VALUE	VARCHAR2	20	null	null	null	The value.