T-SQL Challenging Product

[R2d2Rabeau]

I need some advice:
I have the following table:

Id - Desc -- Level -- Parent -- Value
1 -- aaaa ------ 1 -------- 0 -- --- -- null ---- >> 1.5 * 4 = 6
2 -- doz ----- -- 2 -------- 1 --- ---- - 44
3 -- bb ------ -- 3 ------ -- 2 ---- ----- 1.5
4 -- cc ------ -- 3 ------ -- 2 ---- ----- 4
5 -- bbbb --- -- 1 -------- 0 -- -- --- null ---- >> 5 * 2 = 10
6 -- roz ----- -- 2 -------- 5 --- ---- -- 77
7 -- bb ------ -- 3 -------- 6 ---- ----- - 5
8 -- cc --- --- -- 3 ------ -- 6 ---- ----- 2

I want to insert the product ( bb * cc) into aaaa (id =1)
as shown in itallic.

Can you suggest an efficient wayt to do that?

Thank you for your help.

[SkinHead]

Not sure what you want to do.

Do you mean UPDATE the row ID=1, DESC='aaaa' ?

Do you want to INSERT a new row ?

When you say "insert the product ( bb * cc) into aaaa (id =1)" - Is this something to do with the rows having DESC='bb' and DESC='cc'

Maybe it's me being incredibly thick, but a little more explanation would be good