What if the record matching join condition do not meet what will print then?

Answer 1

If it's an inner join (which is the default), the result will be nothing. If it's an outer join (either left or right), you'll get some results, as long as the left (respectively right) table meets the part of the condition that is not the join condition.

Answer 2

Correct. And I believe that if it is an outer join you can make it show all the data where this is a matching primary key.