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Warning:
CockroachDB v19.2 is no longer supported. For more details, see the Release Support Policy.
The COMMENT ON statement associates comments to databases, tables, or columns.
Required privileges
The user must have the CREATE privilege on the object they are commenting on.
Synopsis
Parameters
| Parameter | Description |
|---|---|
database_name |
The name of the database you are commenting on. |
table_name |
The name of the table you are commenting on. |
column_name |
The name of the column you are commenting on. |
comment_text |
The comment (STRING) you are associating to the object. |
Examples
Setup
The following examples use MovR, a fictional vehicle-sharing application, to demonstrate CockroachDB SQL statements. For more information about the MovR example application and dataset, see MovR: A Global Vehicle-sharing App.
To follow along, run cockroach demo to start a temporary, in-memory cluster with the movr dataset preloaded:
$ cockroach demo
Add a comment to a database
To add a comment to a database:
> COMMENT ON DATABASE movr IS 'This database contains information about users, vehicles, and rides.';
To view database comments, use SHOW DATABASES:
> SHOW DATABASES WITH COMMENT;
database_name | comment
+---------------+-------------------------------------------------------------------+
defaultdb | NULL
movr | This database contains information about users, vehicles, and rides.
postgres | NULL
system | NULL
(4 rows)
Add a comment to a table
To add a comment to a table:
> COMMENT ON TABLE vehicles IS 'This table contains information about vehicles registered with MovR.';
To view table comments, use SHOW TABLES:
> SHOW TABLES FROM movr WITH COMMENT;
table_name | comment
+----------------------------+----------------------------------------------------------------------+
users |
vehicles | This table contains information about vehicles registered with MovR.
rides |
vehicle_location_histories |
promo_codes |
user_promo_codes |
(6 rows)
Add a comment to a column
To add a comment to a column:
> COMMENT ON COLUMN users.credit_card IS 'This column contains user payment information.';
To view column comments, use SHOW COLUMNS:
> SHOW COLUMNS FROM users WITH COMMENT;
column_name | data_type | is_nullable | column_default | generation_expression | indices | is_hidden | comment
+-------------+-----------+-------------+----------------+-----------------------+-----------+-----------+------------------------------------------------+
id | UUID | false | NULL | | {primary} | false | NULL
city | VARCHAR | false | NULL | | {primary} | false | NULL
name | VARCHAR | true | NULL | | {} | false | NULL
address | VARCHAR | true | NULL | | {} | false | NULL
credit_card | VARCHAR | true | NULL | | {} | false | This column contains user payment information.
(5 rows)
See also
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