COMMENT

Purpose

This statement adds comments about a table or table column, a view, or a view column to the data dictionary.

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

Syntax

/*Add a comment to a column.*/
COMMENT ON COLUMN
    [ schema. ] { table_name.| view_name. } column_name IS 'string';

/*Add a comment to a table or view.*/
COMMENT ON TABLE
    [ schema. ] {table_name | view_name } IS 'string';

Parameters

Examples

• Add a comment to the tbl1 table. You can query the all_tab_comments, dba_tab_comments, or user_tab_comments table to obtain the comment of the table.

  obclient> COMMENT ON TABLE tbl1 IS 'Comment of the tbl1';
  Query OK, 0 rows affected
  

• Add a comment to the name column of the tbl1 table. You can query the all_col_comments, dba_col_comments, or user_col_comments table to obtain the comment of the table column.

  obclient> COMMENT ON COLUMN tbl1.name IS 'Name of person in table tbl1';
  Query OK, 0 rows affected
  

• Delete the comment of the name column of the tbl1 table from the database.

  obclient> COMMENT ON COLUMN tbl1.name IS '';
  Query OK, 0 rows affected
  

• Add a comment to the view1 view. You can query the all_tab_comments, dba_tab_comments, or user_tab_comments table to obtain the comment of the view.

  obclient> CREATE VIEW view1 AS SELECT * FROM tbl1;
  Query OK, 0 rows affected
  
  obclient> COMMENT ON TABLE view1 IS 'Comment of the view1';
  Query OK, 0 rows affected
  

• Add a comment to the name column of the view1 view. You can query the all_col_comments, dba_col_comments, or user_col_comments table to obtain the comment of the view column.

  obclient> COMMENT ON COLUMN view1.name IS 'Name of person in view view1';
  Query OK, 0 rows affected
  

• Delete the comment of the name column of the view1 view from the database.

  obclient> COMMENT ON COLUMN view1.name IS '';
  Query OK, 0 rows affected