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  1. #1
    Join Date
    Oct 2015

    ER Diagram from an problem from an university exam

    at my university i had an exam and the last problem [so the most difficult part of it ]
    sound like this:
    A health care centre is planning to manage its population of chronic disease patients using wearable electronic medical devices to monitor health parameters. The devices worn by a patient form a Personal Area Network1 (PAN), communicating through Continua2 protocols with a smart phone, which acts as a gateway to the medical centre. Most of the patients will only wear reading devices (sensors), to monitor health parameters, such as the heartbeat and glucose level, but some of the patients will also wear output devices (actuators), to control an insulin pump3 or set the speed on a VAD4 . Your task is to design the database of the medical centre to manage the collected readings and settings of monitored patient devices.
    A more detailed description follows:
    A medical device can be an input sensor (glucose meter), an actuator (insulin pump) or both. Every device has a serial number from its manufacturer and a description (e.g., “blood pressure meter” or “insulin pump+glucose meter”). Devices handle readings and writings of values of physical measures, such as glucose level (5.9 mmol/L), temperature (37.8 ºC), rotating speed (2000 RPM) or voltage (35 mV). These values and the times of observation/setting are to be recorded in the database. Actuators receive "settings" of values at specific times (e.g., setting the rotating speed of a pump to 2000 RPM). Sensors can collect “readings", sets of values at specific times. For instance, a device for measuring the heart rate could send the last 60 values sampled in the past hour to be stored on the database associated to the time of collecting that data from the sensor; in that case, an example reading would store the signal as 60 name-value pairs (“minute 00” : 75, “minute 01” : 78, … “minute 59” : 125) associated to "Wed Sep 30 23:58:29 WEST 2015”. Another case is a blood pressure meter which collects in each reading two name-value pairs (e.g., “min” : 7.2 and “max” : 13.8).
    The wearable devices of a patient are connected to a patient's PAN. A given device is connected to one (and only one) PAN during a time period, but may be disconnected after some time (for instance, to be replaced or connected to the PAN of another patient), or even reconnected again (for instance, after a repair).
    Patients who carry wearable devices have a PAN (in practice a smart phone, and no more than one PAN per patient!). The PAN is used to transfer data (readings and settings) between the wireless medical devices and the database in the medical centre. PANs, each identified by a unique internet domain name (“”), have a mobile phone number. PANs are worn by patients over some periods (when prescribed), but a patient may replace a PAN for another PAN after some time (for instance, a given PAN that was used by a recovered patient may be assigned later to a new patient).
    In the medical centre, we also keep track of the municipalities where each patient is living over different periods of time (“Joe lived in Cascais from 1-dec-2011 to 31-mar-2013 and in Lisbon since then”). We also keep track of the periods in which two patients have cohabitated (“Joe lived with Mary from 1-dec-2011 to 31-mar-2013 and has been living with Nicole since 30-apr-2014”). The database has the name, address and the (unique) National Health Service number of each patient: a municipality has a name and a unique 5 digit code (assigned by the National Bureau of Statistics).
    Note: To encode periods that have not ended in the database, i.e., periods spanning from sometime ago to the present you could set the final date of the period to a special date, e.g. Dec 31st , 2999. For instance, to encode that a blood pressure device is connected to PAN since September 28th, 2015 until now, or a patient who moved to the municipality of Lisbon the same date, we would set the start and end dates of the relevant periods to “Mon Sep 28 00:00:00 WEST 2015” and “Tue Dec 31 00:00:00 WEST 2999”, respectively.

    i have tried to do it but i had some difficulties, i have made this:

    i dont think that it is right, especially the things that i have in the agregation.
    but i have wrote something with the hope to get some points in the exam mark

    so can u help me guys tell me what i have done wrong or to correct my diagram?

    PS: a offer free beer to those who will help me

    i have used the DIA software to draw the diagram:

    the source file is the following

    i thank u in advance for the help

  2. #2
    Join Date
    Oct 2015
    so, nobody is able to help me?

  3. #3
    Join Date
    Feb 2004
    In front of the computer
    Quote Originally Posted by dbpirate View Post
    so, nobody is able to help me?
    Keep in mind that you're expecting professionals to volunteer to help you with your assignment. While you might get a quick response, that expectation is unfounded... Give people a week or so and you're more likely to get the kind of response that you'd like.

    In theory, theory and practice are identical. In practice, theory and practice are unrelated.

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