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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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