MySQL: How do I add a string on row X2 with ID Y1 in column Z1 to row X1 with ID Y1 to column Z1?

TABLE A
Row  IdA ValueA
1    1   ABCD
2    2   EFGH
3    开发者_如何学编程3   IJKL

TABLE B
Row IdB ValueB
1   1   QWER
2   2   TYUI
3   3   OPAS

CONNECTOR X
Row  IdA  IdB
1     1    1
2     1    2
3     2    3

I want the output to display:

OUTPUT
Value A --- ValueB(1), ValueB(2)
ABCD    --- QWER, TYUI

So, basically, every time there's a doublet in the connector table's IdA column, those two (or more) entries merge the strings in the Value field for my output.

Is this even doable with a MySQL query, or do I -have- to resort to sorting through the whole database with a PHP array? I'd rather like to avoid that, if at all possible!

I've looked at the various JOINs to no avail and thought about using a GROUP BY and COUNT(DISTINCT ...) query, but it just seems a very inelegant way to go about it. Suggestions are welcome!

SELECT a.ValueA, GROUP_CONCAT( b.ValueB SEPARATOR ', ' ) AS ValuesB
FROM connector c
JOIN tblA a ON c.IdA = a.IdA
JOIN tblB b ON c.IdB = b.IdB
GROUP BY a.IdA

Will give you results:

+--------+------------+
| ValueA | ValuesB    |
+--------+------------+
| ABCD   | QWER, TYUI |
| EFGH   | OPAS       |
+--------+------------+