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Real-Time Charting of Electrical Sensor Data

Let’s look at how we can display real-time and historical sensor data for Household Electrical usage using sqlDashboards.

The historical data is taken from the UCI Machine Learning Repository. This is a single CSV file with 1 minute readings between December 2006 and November 2010. i.e.

The Sensor Data Sql Dashboard

sql dashboard of household electric sensor data

Time Series Data Format

The data came in the following format:

date time Global_active_power Global_reactive_power
2006-12-16 17:24:00 4.216 0.418
2006-12-16 17:25:00 5.36 0.436
2006-12-16 17:26:00 5.374 0.498

Where the columns have the following meaning:

  • date: Date in format dd/mm/yyyy
  • time: time in format hh:mm:ss
  • global_active_power: household global minute-averaged active power (in kilowatt)
  • global_reactive_power: household global minute-averaged reactive power (in kilowatt)
  • voltage: minute-averaged voltage (in volt)
  • global_intensity: household global minute-averaged current intensity (in ampere)
  • sub_metering_1: energy sub-metering No. 1 (in watt-hour of active energy). It corresponds to the kitchen, containing mainly a dishwasher, an oven and a microwave (hot plates are not electric but gas powered).
  • sub_metering_2: energy sub-metering No. 2 (in watt-hour of active energy). It corresponds to the laundry room, containing a washing-machine, a tumble-drier, a refrigerator and a light.
  • sub_metering_3: energy sub-metering No. 3 (in watt-hour of active energy). It corresponds to an electric water-heater and an air-conditioner.

Creating the SQL Dashboard Charts

To create the live charts I:

  1. Imported the data to MySQL database.
  2. [raw]


  3. Created a java process to insert live sensor data.
  4. Opened sqlDashboards
  5. Added a time series monthly graph and using the sql query:

    select STR_TO_DATE(DATE_FORMAT(Date, '%Y-%m-01'),'%Y-%m'),AVG(Global_active_power),AVG(Global_reactive_power) FROM power GROUP BY DATE_FORMAT(Date, '%Y-%m-01')
  6. Added a daily time series rollup graph and using the sql query:

    CREATE TABLE daily AS select Date,AVG(Global_active_power),AVG(Global_reactive_power) FROM power WHERE Date>'2009-11-11' GROUP BY Date;
  7. Added a bar chart showing the different meter readings as bar charts per year:

    select CAST(YEAR(Date) AS CHAR(4)) AS Year,AVG(Sub_metering_1),AVG(Sub_metering_2),AVG(Sub_metering_3) from power GROUP BY YEAR(Date)
  8. Added further queries to show the live data for today…

This gave me the final dashboard:
Sensor Data time Series Sql Charts




I came across this interesting post on ASCII pie charts for MySQL. I thought I’d use our command line tool sqlChart todraw the database pie chart instead.



Simply changing our mysql command to sqlchart and adding the additional arguments
"-o c:\temp\aa\sizes.png -c piechart"
gives us the following SQL Pie Chart:

MySQL Sakila Table Sizes Pie Chart

MySQL Sakila Table Sizes Pie Chart

Notice because sqlchart’s command line arguments closely resemble the mysql command line options, we can quickly change the calls from querying to graphing.