I want to join two tables, removing duplicate values

I have to say I’m an amateur on MySQL, plus english is not my mother’s language.

Here is my first table “Teacher”:

ID Name         Procedence
1  John         Italy
2  Mike         Russia
3  Lauren       Spain
4  Arnold       Spain

And here my second table “Course”:

ID1  CourseName
1    Sailing
1    Football
2    Basketball
2    Hockey

I would like to know which country has more teachers giving courses, but I don’t want that it count the same teacher twice. So far I made this:

SELECT Procedence, Count(Procedence) as Procedence_Count 
from Teacher INNER JOIN Course
ON Course.ID1 = Teacher.ID
GROUP by Procedence
having Procedence_Count > 1;

When I run this, I obtain:

Procedence    Procedence_Count
Italy         2
Russia        2

But the code counts John and Mike as two persons, I would like to remove that duplicity, so I would like to obtain:

Procedence    Procedence_Count
Italy         1
Russia        1

Thanks a lot.

Answer

Use count(distinct):

select Procedence, Count(distinct t.id) as teacher_count 
from Teacher t join
     Course c
     on c.ID1 = t.ID
group by Procedence
having teacher_count > 1;

One additional note: “procedence” is not at all a common English word. One word is “provenance”. I think more commonly “origin” or just “country” would be used.