demo:
select * from ( select * from DEV_REG_CFG_CAMERA where 1 = 1 order by unid asc) where rownum < 3001 minus select * from ( select * from DEV_REG_CFG_CAMERA where 1 = 1 order by unid asc) where rownum < 1
minus是差集的意思，、
以上sql的意思是，查询DEV_REG_CFG_CAMERA中以unid字段排序后，取前3000条。