mysql 多表查询

select count(*) from
99_wuguan.wg_buildings,
99_wuguan.wg_building_enormous,
99_wuguan.wg_building_unit,
99_wuguan.wg_building_house
where
99_wuguan.wg_buildings.Id = 1
and 99_wuguan.wg_buildings.Id = 99_wuguan.wg_building_enormous.building_id
and 99_wuguan.wg_building_enormous.Id = 99_wuguan.wg_building_unit.enormous_id
and 99_wuguan.wg_building_unit.Id = 99_wuguan.wg_building_house.unit_id

Mysql 多表联合查询效率分析及优化