Well if you want to add drops, You can use this
UPDATE [PS_GameDefs].[dbo].[MobItems]
SET [MobItems].[Grade] =
WHERE [MobItems].[MobID] = AND [MobItems].[ItemOrder] =
AND [MobItems].[DropRate] =
Personally i find it easier to edit mobs individually,Via the MobItems.dbo
But if you want to Delete Items from mobs the query as far as i can work out would be along these lines or atleast something to this effect,
UPDATE [PS_GameDefs].[dbo].[MobItems]
SET [Mobitems].[GRADE] = 0
WHERE [MobItems.[MobID] = all AND [MobItems].[ItemOrder] = all
AND [MobItems].[DropRate] = 0
Dont Quote me on that last one Mind you
Unless your asking for someones MobItems.Dbo In which case your better off Grabbing one from a Database Download & Transfering it into your own database.