composite primary key vs. primary key on additional single column

From: ciapecki <ciapecki_at_gmail.com>
Date: Sun, 22 Mar 2009 14:05:53 -0700 (PDT)
Message-ID: <2eb21c9e-a8a6-4d55-b11b-c3fcf8b3716d_at_w34g2000yqm.googlegroups.com>

we have 2 tables: individuals1 with primary key on ind1_id (numeric field) and individuals2 on ind2_id (varchar2 field)

individuals1 has as well ind2_id populated for some rows (not all) individuals2 has as well ind1_id populated for some rows (not all) both tables have common attributes e.g. first_name, last_name

As a requirement I need to have a new table (combined_inds) with all the data from individuals1 and from individuals2 which will look like this:
[ind1_id, ind2_id, first_name, last_name] this structure will have many NULLs in both ind1_id and many NULLs in ind2_id, but at least one non-NULL value for these attributes for every row.

now I would like to create a primary key on that new table.

Is it better to have a composite primary key on both ind1_id, ind2_id? or maybe it's better to populate a new column that would hold concatenation of both of those columns, and then do the primary_key constraint on that?

thanks,
chris Received on Sun Mar 22 2009 - 16:05:53 CDT