Aquí hay un ejemplo que hace una unión entre dos tablas completamente no relacionadas:la tabla Student y Products. Genera una salida de 4 columnas:
select
FirstName as Column1,
LastName as Column2,
email as Column3,
null as Column4
from
Student
union
select
ProductName as Column1,
QuantityPerUnit as Column2,
null as Column3,
UnitsInStock as Column4
from
Products
Obviamente modificará esto para su propio entorno...