我有一张叫做城市的桌子:
+------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+------------+--------------+------+-----+---------+----------------+
| id | bigint(20) | NO | PRI | NULL | auto_increment |
| country_id | mediumint(9) | NO | MUL | NULL | |
| region_id | bigint(20) | NO | MUL | NULL | |
| city | varchar(45) | NO | | NULL | |
| latitude | float(18,2) | NO | | NULL | |
| longitude | float(18,2) | …