Recursive query for Product Tree

I have product tree for a product

product_tree table :
product_code, stock_code, amount_ratio
152.001.001, 151.001.001, 1
152.001.001, 150.001.001, 2
151.001.001 150.003.003, 3
151.001.001 150.009.001, 1

I need to write a query with result:

152.001.001, 150.003.003, 1
152.001.001, 150.009.001, 1
152.001.001, 150.001.001, 2

i.e. for 151 we have another node and i do not wanna see 151 here...but its
ingredients..

it is kind of recursive query how can i write it ? any help?

Thx in advance

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