我在关系数据库中有以下表:
[Sensor]
LocationId [PK / FK -> Location]
SensorNo [PK]
[AnalogSensor]
LocationId [PK/FK -> Sensor]
SensorNo [PK/FK -> Sensor]
UpperLimit
LowerLimit
[SwitchSensor]
LocationId [PK/FK -> Sensor]
SensorNo [PK/FK -> Sensor]
OnTimeLimit
[Reading]
LocationId [PK/FK -> Sensor]
SensorNo [PK/FK -> Sensor]
ReadingDtm [PK]
[ReadingSwitch]
LocationId [PK/FK -> Reading]
SensorNo [PK/FK -> Reading]
ReadingDtm [PK/FK -> Reading]
Switch
[ReadingValue]
LocationId [PK/FK -> Reading]
SensorNo [PK/FK -> Reading]
ReadingDtm [PK/FK -> Reading]
Value
[Alert]
LocationId [PK/FK -> Reading]
SensorNo [PK/FK -> Reading]
ReadingDtm …