You don't specify which scanners, but I assume the database-driven scanners like HomePatrol-1/2 and newer models. Short answer is yes, as long as it supports the P25 system, at the very least.
San Diego County, as with many counties throughout California, has unified their city and county-wide services into a regional P25 trunked system that is accessable to any scanner capable of receiving such.
And yes, the database is still kept up, every week.
(I own a HomePatrol-2 with the Extreme upgrade- Worth it!- and yes, I've used it when I've visited San Diego. I live in the opposite end of the state, in Humboldt County, and we're about to do the same as so many counties have, throughout the state.)