Question about comment command

Question

I have to update comments on a lot of tables. I want to only update date them when the field is null.
Does anyone know how this can be accomplished?
I want something like COMMENT ON COLUMN TEST.REPORTS.ID IS 'Primary Key' where TEST.REPORT.ID IS NULL;
Howard

Answer 1

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I have to update comments on a lot of tables. I want to only update date them when the field is null.
Does anyone know how this can be accomplished?
I want something like COMMENT ON COLUMN TEST.REPORTS.ID IS 'Primary Key' where TEST.REPORT.ID IS NULL;
>
While adding comments can definitely be valuable I would suggest you take a different approach.
1. Add comments at the table level first. The ALL_TAB_COMMENTS view lists OWNER, TABLE_NAME, TABLE_TYPE, COMMENTS. Then for column level comments it is the ALL_COL_COMMENTS view with OWNER, TABLE_NAME, COLUMN_NAME, COMMENTS.
http://docs.oracle.com/cd/B28359_01/server.111/b28320/statviews_2092.htm#sthref1463
2. Prioritize the tables you add comments to. Focus first on your most important key tables and columns. Adding comments to those will be more immediately useful than a shotgun approach to try to add comments to all tables and columns. Most environments have hundreds or thousands of tables so take care of the important ones first.
3. A simple way to get started on your task is to create your own tables that are clones of the system views
create table my_tab_comments as select * from user_tab_comments; -- or from ALL_TAB_COMMENTS with/without OWNER='SCOTT' e.g.
create table my_col_comments as select * from user_col_comments
alter table my_tab_comments add (modified_date date default sysdate)
alter table my_col_comments add (modified_date date default sysdate)These tables become your working data and every record has a date.
If you use a GUI like Oracle's free sql developer tool you can easily update the COMMENTS columns that are null and update the MODIFIED_DATE accordingly. You can also see the existing comments and perhaps update them if necessary.
When you are ready to apply your changes use a script similar to what sb92075 has posted to extract the data from YOUR tables and create ALTER statements that will apply your comments.
You can easily modify the script to apply just one table at a time if you want.
By using your own work tables you make it easier to see what comments have already been written and to do the update is smaller, more manageable pieces. You can also let other developers comment their own tables so one person doesn't have to do it all.
If you add new tables to a schema later it is easy to write a query to add them to your custom tables and create comments.
When the project is finished you can either export your MY_TAB_COMMENTS and MY_COL_COMMENTS tables to a delimited, or Excel, file or create a big script to put into your version control system.
That way you won't have to repeat the process later.