> ## Documentation Index
> Fetch the complete documentation index at: https://docs.firebolt.io/llms.txt
> Use this file to discover all available pages before exploring further.

<AgentInstructions>

## Submitting Feedback

If you encounter incorrect, outdated, or confusing documentation on this page, submit feedback:

POST https://docs.firebolt.io/feedback

```json
{
  "path": "/reference-sql/commands/data-definition/comment-on",
  "feedback": "Description of the issue"
}
```

Only submit feedback when you have something specific and actionable to report.

</AgentInstructions>

> Reference and syntax for the COMMENT ON statement.

# COMMENT ON

Adds or modifies a description (comment) for objects in your Firebolt account. Comments provide descriptive metadata to help document the purpose and usage of database objects, making it easier to understand and maintain your data structures.

The COMMENT ON statement supports adding comments to the following object types:

* LOCATION - External data source connection objects
* DATABASE - Database objects
* TABLE - Table objects
* COLUMN - Individual table columns
* ENGINE - Engine objects

Comments are stored as metadata and can be queried through the information\_schema views. You can set a comment to any string, update an existing comment, remove a comment by setting it to NULL, or set it to an empty string.

## Syntax

```sql theme={"theme":{"light":"github-light","dark":"github-dark"}}
-- Location comment
COMMENT ON LOCATION <location_name> IS { '<comment_string>' | NULL }

-- Database comment  
COMMENT ON DATABASE <database_name> IS { '<comment_string>' | NULL }

-- Table comment
COMMENT ON TABLE [<database_name>.]<table_name> IS { '<comment_string>' | NULL }

-- Column comment
COMMENT ON COLUMN [<database_name>.[<schema_name>.]]<table_name>.<column_name> IS { '<comment_string>' | NULL }

-- Engine comment
COMMENT ON ENGINE <engine_name> IS { '<comment_string>' | NULL }
```

## Parameters

| Parameter          | Description                                                                          |
| :----------------- | :----------------------------------------------------------------------------------- |
| `<location_name>`  | The name of the location object to comment on.                                       |
| `<database_name>`  | The name of the database to comment on, or the database containing the table/column. |
| `<table_name>`     | The name of the table to comment on, or the table containing the column.             |
| `<schema_name>`    | Optional schema name. Defaults to public if not specified.                           |
| `<column_name>`    | The name of the column to comment on.                                                |
| `<engine_name>`    | The name of the engine to comment on.                                                |
| `<comment_string>` | A text string describing the object. Must be enclosed in single quotes.              |
| NULL               | Removes an existing comment from the object.                                         |

## Examples

The following example sets a description:

```sql theme={"theme":{"light":"github-light","dark":"github-dark"}}
-- Location
COMMENT ON LOCATION my_location IS 'my comment';

-- Database
COMMENT ON DATABASE my_database IS 'my comment';

-- Table
COMMENT ON TABLE my_table IS 'my comment';

-- Column
COMMENT ON COLUMN my_table.my_column IS 'my comment';

-- Engine
COMMENT ON ENGINE my_engine IS 'my comment';
```

The following example removes a description:

```sql theme={"theme":{"light":"github-light","dark":"github-dark"}}
-- Location
COMMENT ON LOCATION my_location IS NULL;

-- Database
COMMENT ON DATABASE my_database IS NULL;

-- Table
COMMENT ON TABLE my_table IS NULL;

-- Column
COMMENT ON COLUMN  my_table.my_column IS NULL;

-- Engine
COMMENT ON ENGINE my_engine IS NULL;
```