Single Unit Limit
There are a number of specific conditions that must be met for a property owner to use owner occupancy as Just Cause for evicting a tenant. One condition that must be met post Proposition G (which went into effect Nov 1998) is that a property may only have one owner-occupancy eviction. This restriction applies FOREVER regardless if the property is resold (notwithstanding a few hardship exemptions).
In other words, before purchasing a property it is worth learning whether there is a prior owner-occupancy eviction in the building as the existence of one may limit your move-in options as a property owner. Moreover, before a property owner considers an owner-occupancy eviction it may be beneficial to consider the long term ramifications to the property in terms of resale value and rental property flexibility.