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Search found 28 results on 2 pages for 'jarrod roberson'.

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• mySQL Left Join on multiple tables

  - by Jarrod

  Hi I'm really struggling with this query. I have 4 tables (http://oberto.co.nz/db-sql.png): Invoice_Payement, Invoice, Client and Calendar. I'm trying to create a report by summing up the 'paid_amount' col, in Invoice_Payment, by month/year. The query needs to include all months, even those with no data There query needs the condition (Invoice table): registered_id = [id] I have tried with the below query, which works, but falls short when 'paid_date' does not have any records for a month. The outcome is that month does not show in the results I added a Calendar table to resolved this but not sure how to left join to it. SELECT MONTHNAME(Invoice_Payments.date_paid) as month, SUM(Invoice_Payments.paid_amount) AS total FROM Invoice, Client, Invoice_Payments WHERE Client.registered_id = 1 AND Client.id = Invoice.client_id And Invoice.id = Invoice_Payments.invoice_id AND date_paid IS NOT NULL GROUP BY YEAR(Invoice_Payments.date_paid), MONTH(Invoice_Payments.date_paid) Please see the above link for a basic ERD diagram of my scenario. Thanks for reading. I've posted this Q before but I think I worded it badly.

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• Can a MAC address be used as a reliable part of a rights management (DRM) scheme?

  - by Jarrod Mosen

  We're currently writing some software that we want to protect. We thought that registering a user's MAC address in a database upon activation of the software seemed viable; we can profile and grab that with a Java applet, (is there a better way?) so getting it isn't too much of a problem. However, we want their computer to only run the application, and download application files/updates from the server when their MAC address has been verified with their one on-file. We understand that this means a lockdown to one computer, but special changes can be made on request. What would be the best way to verify their MAC address, to see if it exists in the database, and then serve them the files to run the application? (And to simply run it on subsequent requests, to prevent re-downloading.)

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• Implementing Model-level caching

  - by Byron

  I was posting some comments in a related question about MVC caching and some questions about actual implementation came up. How does one implement a Model-level cache that works transparently without the developer needing to manually cache, yet still remains efficient? I would keep my caching responsibilities firmly within the model. It is none of the controller's or view's business where the model is getting data. All they care about is that when data is requested, data is provided - this is how the MVC paradigm is supposed to work. (Source: Post by Jarrod) The reason I am skeptical is because caching should usually not be done unless there is a real need, and shouldn't be done for things like search results. So somehow the Model itself has to know whether or not the SELECT statement being issued to it worthy of being cached. Wouldn't the Model have to be astronomically smart, and/or store statistics of what is being most often queried over a long period of time in order to accurately make a decision? And wouldn't the overhead of all this make the caching useless anyway? Also, how would you uniquely identify a query from another query (or more accurately, a resultset from another resultset)? What about if you're using prepared statements, with only the parameters changing according to user input? Another poster said this: I would suggest using the md5 hash of your query combined with a serialized version of your input arguments. This would require twice the number of serialization options. I was under the impression that serialization was quite expensive, and for large inputs this might be even worse than just re-querying. And is the minuscule chance of collision worth worrying about? Conceptually, caching in the Model seems like a good idea to me, but it seems in practicality the developer should have direct control over caching and write it into the controller. Thoughts/ideas? Edit: I'm using PHP and MySQL if that helps to narrow your focus.

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