How do I get every permutation in two totally unrelated tables with t-sql

Question

I have two tables that are indirectly related by another table

TableA - ID, SomeFieldA

TableB - ID, SomeFieldB

TableAB - IDA, IDB, SomeFiel

Answer 1

You can do this:

select
    a.*, b.*
from
    a, b

This will do a cross join which will give you all possible combinations.

From there, it's simple to use that within the context of an INSERT statement to populate your AB table.