simpler table joining for many to many

many_to_many.sql

with a_b_name_in(table_a_name, table_b_name)
as (
    values
        ('table a 1', 'table b 1'),
        ('table a 2', 'table b 1'),
)
insert into a_b (a_id, b_name)
select a.id, b.id
from a_b_name_in
inner join table_a
    on a_b_name_in.table_a_name = table_a.id
inner join table_b
    on a_b_name_in.table_b_name = table_b.id