How to disable items from db?

Hello buddies,
I wanna know that how can i disable some items from db?
For example as i want to change the drop of 12dg som and sun items.So i want to make it undroppable.
I would be glad if somebody can tell me the solution.

Find the _RARE 12D entries in objCommon and change service to 0. May want to do it in the items table too, just find the number you get in the link column and then set services to 0 there too.

Edit: I'm not sure why you don't want them to drop from mobs but if it's because you're gonna be selling them from npcs or selling them for silk or something then you wont be able to do this by setting service to 0, in this case to simply stop mobs from dropping them then set the ProbGroup12 column in _RefDropClassSel_Equip to 0.

Because it makes characters kinda overpowered and i wanna make em undroppable
btw thank your for your answer,im gonna try it when i can :)