Re: Student SQL question

From: Neil Chandler <oracle_at_tchp2.tcamuk.stratus.com>
Date: 19 May 1998 11:42:56 GMT
Message-ID: <slrn6m2ruq.cda.oracle@tchp2.tcamuk.stratus.com>

In article <01bd8279$03db4f80$049a0580_at_mcb>, "Matt Brennan" wrote:

>
>> 2. Once a table is created, a column in that table cannot be deleted
>
>True. You have to drop the table and then re-create the table. Save the
>existing rows in another table first and then re-insert them in the new
>table. I think that's dumb, but what can you do? I don't know why Oracle
>won't let you drop a column. One would think it's the easiest thing to do,
>as opposed to modifying an existing column.
>

I always thought it was down to referential integrity. It cannot be THAT difficult to cascade the delete to integrity constraints.

I suspect the way that the data dictionary has been designed has a major part to play with Oracle not providing this functionality.

>>or a datatype of a column cannot be changed
>
>Not true. But all rows have to have a null value for the column in order
>to do it.
>
>>the tablename cannot be changed (as far as I know)
>
>Haven't tried that myself, but I saw a post where someone else answered it.

RENAME table_name TO new_table_name;

Note: You cannot rename indexes and they do not get renamed with this operation.

Neil Chandler
TCAM Systems (UK) Ltd.
Oracle DBA. Received on Tue May 19 1998 - 06:42:56 CDT