Point query example

A nationwide convenience store corporation uses a remote SqlServer database to archive fuel sales records from each of its stores. The database stores records for three types of fuel every 15 minutes. To graphically display updated information over the Internet, the store uses the RdbmsNetwork and the Point Device Extension, as demonstrated below:

1. Each store exports transaction histories from its controller via a Supervisor, to a central SqlServer database using the Sql Server History Device Ext and the History Export Manager view.

   
   
   

   Note: Embedded controllers support only the HsqlDbDatabase.

2. For each store, a Supervisor station creates proxy points for each fuel type, by creating and configuring an RdbmsPointQuery for each fuel type.

   
   
   

3. An Sql query displays the total fuel sold as of the latest update.

   
   
   

   This counter is scheduled to update every 15 minutes, providing a total that updates every 15 minutes along with the time of the update.

   In this example, these Sql parameters are optional:

   • “1 AS myKey” creates a new column as a key column and is not required.

   • “1 AS Total”, “AS Time”, and “AS Status” create titles for the respective columns. If these optional parameters are not used, columns are titled “column1”, “column2”, “column3”, respectively.

4. Data are discovered and added under the Rdbms Point Device Extension node.

   
   
   

5. Once added to the RdbmsNetwork, these proxy points are used to graphically display total gallons of each fuel type sold as of the update time.