How to check the existence of two columns' data in two different tables ? MySQL

Question

I have two different tables in two different databases ..

what I want to do is to check if the data of two columns exist in the other table .. if it does exist count

Answer 1

If I'm understanding you correctly, one option is to use exists:

select * 
from table1 t1
where exists (
    select 1
    from table2 t2 
    where t1.column1 = t2.column1 and
          t1.column2 = t2.column2
)

This will return a list of rows from the first table that have a corresponding matching row in the second.

Answer 2

Do an INNER JOIN on both tables:

SELECT COUNT(*)
FROM table_1 t1
INNER JOIN table_2 t2
    ON t1.column_1 = t2.column_1
    AND t1.column_2 = t2.column_2