Joining SQL queries with where clause

Question

I have 2 tables in a MYSQL database wich look like this:

Klant:

ID  Naam           Email    Soort  Status
6   test           test     test2   
7   status test    test     test    20
8   soort test     test     test    
9   soort test 2   test2    Museum  

Mail:

ID  Content                 Datum       Titel 
1   (lots of encoded HTML)  18-03-13    test
2   (lots of encoded HTML)  18-03-13    test2
4   (lots of encoded HTML)  18-03-13    alles weer testen

(yes, I'm still testing alot^^)

Now I have a SQL query that selects all from 'Klant' with a where clause which gets the ID from a previous page:

$strSQL = "SELECT * FROM Klant WHERE ID =  '".$_GET["ID"]."' ";  

What I want is to JOIN this query with the following query:

SELECT ID, Titel FROM Mail; 

EDIT:

From all your answers and comments I think I begin to think my question maybe is totally wrong.. I'll explain where I need it for and I might not even need JOIN? I currently have a table wich includes the data from 'Klant' which looks like this:

The meaning is that I add another table which includes all the ID's and Title's from 'Mail'. I am sorry for the confusion I may have caused with you since I wasn't that clear with my question. I hope that this may clear up what I want and you guys can maybe tell me if I even need to JOIN this or can I do something else?

I am still a student and this is the first time I've had to use JOIN and I can't figure this out. If anyone can show me how to do this or push me in the right direction it would be great!

Answer 1

SELECT * FROM Klant t1
JOIN
SELECT ID, Titel FROM Mail t2
ON t1.ID = t2.ID
WHERE t1.Name  = 'test'

To have the desired result do the following:

SELECT * FROM Klant t1
JOIN
SELECT ID, Titel FROM Mail t2
ON t1.ID = t2.ID

And if you want to have a specific row than just add the where clause:

WHERE t1.ID = 6

or

WHERE t1.Naam = 'test'

and so on