Like shown below. I am simply using the update statement you had posted and replacing the right side with Jim's code (in red)update IM_ITEM
set IM_ITEM.PROF_COD_3 =
ROUND( SUBSTRING(USR_ITEM_PROMO,PATINDEX('%[0-9]%',USR_ITEM_PROMO),
PATINDEX('%[%]%',USR_ITEM_PROMO)-PATINDEX('%[0-9]%',USR_ITEM_PROMO) ),0)
where PO_VEND.USR_ITEM_PROMO is not null