How to get table comments via SQL in Oracle?

Question

I've tried :

select * from user_tab_comments; 

and it returns me 3 columns "TABLE_NAME", "TABLE_TYPE", and "COMMENTS", but the "TABLE_NAME" column is like "encrypted", I need clear table names :

TABLE_NAME                      TABLE_TYPE  COMMENTS  BIN$IN1vjtqhTEKcWfn9PshHYg==$0  TABLE       Résultat d'intégration d'une photo numérisée BIN$PUwG3lb3QoazOc4QaC1sjw==$0  TABLE       Motif de fin d'agrément de maître de stage 

When I use select * from user_tables; TABLE_NAME is not "encrypted".

Answer 1

Since 10g Oracle doesn't immediately drop tables when we issue a DROP TABLE statement. Instead it renames them like this BIN$IN1vjtqhTEKcWfn9PshHYg==$0 and puts them in the recycle bin. This allows us to recover tables we didn't mean to drop. Find out more.

Tables in the recycle bin are still tables, so they show up in ALL_TABLES and similar views. So if you only want to see comments relating only to live (non-dropped) tables you need to filter by table name:

select * from all_tab_comments where substr(table_name,1,4) != 'BIN$' / 

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"I can't believe there isn't a flag column so you could do and is_recycled = 0 or something. "

You're right, it would be incredible. So I checked the documentation it turns out Oracle 10g added a column called DROPPED to the USER_/ALL_/DBA_TABLES views.

select tc.*  from all_tab_comments tc      join all_tables t      on tc.owner = t.owner      and tc.table_name = t.table_name where t.dropped = 'NO' / 

Check out the documentation. Obviously the need to join to the ALL_TABLES view requires more typing than filtering on the name, so depending on our need it might just be easier to keep the original WHERE clause.