Skip Headers

Oracle® Database SQL Reference 10g Release 2 (10.2) Part Number B14200-02 |
Home | Book List | Contents | Index | Master Index | Feedback

Previous | Next
| View PDF

# COMMENT

Purpose

Use the `COMMENT` statement to add a comment about a table, view, materialized view, or column into the data dictionary.

To drop a comment from the database, set it to the empty string ' '.

See Also: "Comments" for more information on associating comments with SQL statements and schema objects Oracle Database Reference for information on the data dictionary views that display comments

Prerequisites

The object about which you are adding a comment must be in your own schema or:

- To add a comment to a table, view, or materialized view, you must have `COMMENT` `ANY` `TABLE` system privilege.

- To add a comment to an indextype, you must have the `CREATE` `ANY` `INDEXTYPE` system privilege.

- To add a comment to an operator, you must have the `CREATE` `ANY` `OPERATOR` system privilege.

Syntax

comment::=

Description of the illustration comment.gif

Semantics

TABLE Clause

Specify the schema and name of the table or materialized view to be commented. If you omit `schema`, then Oracle Database assumes the table or materialized view is in your own schema.

Note: In earlier releases, you could use this clause to create a comment on a materialized view. You should now use the `COMMENT` `ON` `MATERIALIZED` `VIEW` clause for materialized views.

COLUMN Clause

Specify the name of the column of a table, view, or materialized view to be commented. If you omit `schema`, then Oracle Database assumes the table, view, or materialized view is in your own schema.

You can view the comments on a particular table or column by querying the data dictionary views `USER_TAB_COMMENTS`, `DBA_TAB_COMMENTS`, or `ALL_TAB_COMMENTS` or `USER_COL_COMMENTS`, `DBA_COL_COMMENTS`, or `ALL_COL_COMMENTS`.

OPERATOR Clause

Specify the name of the operator to be commented. If you omit `schema`, then Oracle Database assumes the operator is in your own schema.

You can view the comments on a particular operator by querying the data dictionary views `USER_OPERATOR_COMMENTS`, `DBA_OPERATOR_COMMENTS`, or `ALL_OPERATOR_COMMENTS`.

INDEXTYPE Clause

Specify the name of the indextype to be commented. If you omit `schema`, then Oracle Database assumes the indextype is in your own schema.

You can view the comments on a particular indextype by querying the data dictionary views `USER_INDEXTYPE_COMMENTS`, `DBA_INDEXTYPE_COMMENTS`, or `ALL_INDEXTYPE_COMMENTS`.

MATERIALIZED VIEW Clause

Specify the name of the materialized view to be commented. If you omit `schema`, then Oracle Database assumes the materialized view is in your own schema.

You can view the comments on a particular materialized view by querying the data dictionary views `USER_MVIEW_COMMENTS`, `DBA_MVIEW_COMMENTS`, or `ALL_MVIEW_COMMENTS`.

IS 'string'

Specify the text of the comment. Please refer to "Text Literals" for a syntax description of `'string'`.

Example

Creating Comments: Example To insert an explanatory remark on the `job_id` column of the `employees` table, you might issue the following statement:

    COMMENT ON COLUMN employees.job_id
       IS 'abbreviated job title';

To drop this comment from the database, issue the following statement:

    COMMENT ON COLUMN employees.job_id IS ' ';