question: public long updateLastVisitTime ( String channelId ) { SQLiteDatabase db = getWritableDatabase ( ) ; long currentTime = System . currentTimeMillis ( ) ; ContentValues values = new ContentValues ( ) ; values . put ( SubscriptionsTable . COL_LAST_VISIT_TIME , currentTime ) ; int count = db . update ( SubscriptionsTable . TABLE_NAME , values , SubscriptionsTable . COL_CHANNEL_ID + " = ?" , new String [ ] { channelId } ) ; return ( count > 0 ? currentTime : - 1 ) ; }
target:  Updates the given channel's last visit time.