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mysql-数据库一对多。多对多关系处理

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Jun 06, 2016 am 09:32 AM

mysql数据库

目前实体。关系为。一台设备必须绑定一张sim卡。一台设备只能绑定在一台车辆上。一台车辆只能属于一个公司。一个公司有多台车辆。设备安装在车辆上。需要填写绑定信息。sim卡安装在设备上是否开通。目前是。设备表。sim表。安装表关键。车辆与设备。车辆表。公司表查询时需要查询某个公司的某台车辆是否绑定某台设备。是否开通

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