Add a 2-column UNIQUE constraint on an existing table in Oracle 7.3.4?

From: Ken Ho <hoke_at_gse.harvard.edu>
Date: 2000/06/02
Message-ID: <3938134b.24348185@news.harvard.edu>#1/1

From SQL Worksheet hitting an Oracle 7.3.4 server I get the following error:

alter table existing_table modify (

     ID                      VARCHAR2(30) not null,
     CODE                VARCHAR2(30) not null
     constraint existing_table_uk unique(id,code));
constraint existing_table_uk unique(id,code))
                                             *

ORA-02253: constraint specification not allowed here

Is there another way to do what I want, namely to add a unique constraint on the combination of the id & code columns in an *existing* table, both of which already are not allowed to be null? Using the similar code for create table does work, but I'd like to avoid recreating the table:

create table new_table (

     ID                      VARCHAR2(30) not null,
     CODE                VARCHAR2(30) not null,
     constraint new_table_uk unique (id,code));

Statement processed. Received on Fri Jun 02 2000 - 00:00:00 CDT