Based on your need you can either concatenate your tables and make it one table or when you just join with no common field its joining to create duplicated information.
You can still join the tables with LEFT JOIN (T1) LOAD * FROM T2. But you will get a cross join. Basically every field is joined with every possible field value the other table. So this can be a usefull technique if you know what you're doing. But it also can cost a lot of GB RAM and makes your computer stop working.