Database question

[Wong Zach-CHZ013]

Hi 
Question: 
Suppose MySQL contains 2 databases, named A and B. 
Database A has table A1, Database B has table B1. 
Both tables A1 and B1 have identical column field names. 
Can MySQL query both A1 and B1 at the same time to form a new table to 
compare 
data in A1 and B1 ? 

Appreciate it. 
Zach