Update data from SQL Script

Question

If my data is the following...
Table: PRODUCT
Field."Item": B03934 SSAPRDIM
SA position 11,12
PR position 13,14
DI position 15,15
I need to break the item number into three and post these three different values into another fields called STONE1, STONE2, STONE3, but i need to do validation with STONE CODE to make sure SA, PR, and DI are the valid value before posting (UPDATE SQL)
how to do it???
UPDATE PRODUCT
SET STONE1
(SELECT substr(item,11,2) p
from product, stone_code
where substr(item,11,2) = stone_code.code)
i am not sure if this is the way to go.

Answer 1

Maybe
update product
   set stone1 = 'SA',
       stone2 = 'PR',
       stone3 = 'DI'
where substr(item,11,6) = 'SAPRDI'or individual treatment of stone ...
update product p
   set (stone1,stone2,stone3) = (select case when substr(item,11,2) = 'SA' then 'SA' end,
                                        case when substr(item,13,2) = 'PR' then 'PR' end,
                                        case when substr(item,15,2) = 'DI' then 'DI' end
                                   from product
                                  where item = p.item
where substr(item,11,2) = 'SA'
    or substr(item,13,2) = 'PR'
    or substr(item,15,2) = 'DI'Regards
Etbin