SQL QUESTION (ADVANCED ??)

I have some problems writing a statement that selects the required information in the following situation:

I have two tables that have an n:m relationship, with an intersection table in between, as follows:

• ------- ------- | A |-------------<| B |>-------------| C |
• ------- -------

The relationships in table B could be like

        A1-C1

	A2-C2
	A2-C3

	A4-C4
	A5-C4
	A5-C5
	A6-C5
	A6-C6
	A4-C6

Now, if I have a value for A, I want to select all other A's that are somehow connected to the given value for A. In case of A4, that would be A4, A5, A6.

The problem is that I don't know how many A's will be in such a 'group', so the use of subselects gives problems. An other problem is that the relations can 'loop'. In above example C6 points back to A4. A connect by clause will loop as well.

The problem can be solved in PL/SQL with some tricks, but I really need one SQL-statement that can do the trick.

Seems to me this is not such an extraordinary case so a solution must be around somewhere and might actually be simple.

Thanks in advance,

Jos.

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