I have two tables, set up as cross reference tables. I would like to extract
data from both to create a third table. It looks like this:

a b c d e
1 name doc-1 doc-b doc-c doc-d
2 joe x
3 ellen x x
4 mike x
5 quinn x x


a b c d e
1 name job-a job-b job-c job-d
2 joe x x
3 ellen x
4 mike x x x
5 quinn x x

a b c d
1 doc first_job second_job third_job
2 doc-a
3 doc-b
4 doc-c
5 doc-d