Can You Compute?

  • Comments posted to this topic are about the content posted at http://www.sqlservercentral.com/columnists/dpoole/canyoucomput

  • Thanks!

  • Wow, what a thorough explaination!  I was tring to explain these concepts to some colleagues over lunch the other day, and your article beats the snot out of my back-of-napkin diagrams!

    Thanks!

  • Very nice.  The graphics you took the time to do the "Alice's Restaurant" thing to really make this a very clear article on what Rollups and Cubes actually do.  The graphics clearly demonstrate why you might want to use the Grouping function of a Rollup or Cube.

    There's lot's of folks who have no idea what a "subtree cost" is, how to determine it, or what unit of measurement it is.  Also, although very obvious from the graphics, simple example Selects for the isolation of subtotals and grandtotals would be very helpful for newbies.  A very brief explanation of these two things would have made this a "six star" article.  

    Outstanding article overall!  Thanks for sharing it with us.

    --Jeff Moden


    RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
    First step towards the paradigm shift of writing Set Based code:
    ________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.
    "Change is inevitable... change for the better is not".

    Helpful Links:
    How to post code problems
    How to Post Performance Problems
    Create a Tally Function (fnTally)
    Intro to Tally Tables and Functions

  • You really did do a nice job on this article. Very complete description and nice use of visualizations to send home.

  • Excellent article.  I had heard of the terms before and had "one day" planned to read up on them thinking they sounded complicated.  You made it sound easy - and as it turns out, it really is

    THANKS

  • I liked it very much. I would like to see more articles like this on the near future. My only "negative" comment is I was reading the article and "copy and paste" the source code and it has a lot typos, here is the code will run:

    SELECT

      Cust.country ,

      Cat.CategoryName ,

      Count(*) AS ProductsBought

     FROM dbo.Customers AS Cust

     INNER JOIN dbo.Orders AS Ord

      ON Cust.CustomerId = Ord.CustomerId

     INNER JOIN dbo.[Order Details] AS OrdDet

      ON Ord.OrderId = OrdDet.OrderId

     INNER JOIN dbo.Products AS Prod

      ON OrdDet.ProductId = Prod.ProductId

     INNER JOIN dbo.Categories AS Cat

      ON Prod.CategoryId = Cat.CategoryId

     GROUP BY

      Cust.Country ,

      Cat.CategoryName

     WITH ROLLUP;

    SELECT Cust.country ,

           Cat.CategoryName ,

           Count(*) AS ProductsBought

     FROM dbo.Customers AS Cust

       INNER JOIN dbo.Orders AS Ord

          ON Cust.CustomerId = Ord.CustomerId

       INNER JOIN dbo.[Order Details] AS OrdDet

          ON Ord.OrderId = OrdDet.OrderId

       INNER JOIN dbo.Products AS Prod

          ON OrdDet.ProductId = Prod.ProductId

       INNER JOIN dbo.Categories AS Cat

          ON Prod.CategoryId = Cat.CategoryId

     GROUP BY

       Cust.Country ,

     Cat.CategoryName

    order by Cust.country;

    GROUP BY clause.

    SELECT

      Cust.country ,

      Cat.CategoryName ,

      Count(*) AS ProductsBought,

      GROUPING(Cust.country) AS SubtotalForCountries,

      GROUPING(Cat.CategoryName) AS SubtotalForCategories

     FROM dbo.Customers AS Cust

     INNER JOIN dbo.Orders AS Ord

      ON Cust.CustomerId = Ord.CustomerId

     INNER JOIN dbo.[Order Details] AS OrdDet

      ON Ord.OrderId = OrdDet.OrderId

     INNER JOIN dbo.Products AS Prod

      ON OrdDet.ProductId = Prod.ProductId

     INNER JOIN dbo.Categories AS Cat

      ON Prod.CategoryId = Cat.CategoryId

     GROUP BY

      Cust.Country ,

      Cat.CategoryName

     WITH CUBE ;

    SELECT

      Prod.ProductId ,

      Prod.ProductName ,

      Cat.CategoryName ,

      Prod.UnitsInStock * Prod.UnitPrice AS StockValue

     FROM dbo.Products AS Prod

     INNER JOIN dbo.Categories AS Cat

      ON Prod.CategoryId = Cat.CategoryId

     ORDER BY

      Cat.CategoryName

     COMPUTE SUM(Prod.UnitsInStock * Prod.UnitPrice);

    SELECT

      Prod.ProductId ,

      Prod.ProductName ,

      Cat.CategoryName ,

      Prod.UnitsInStock * Prod.UnitPrice AS StockValue

     FROM dbo.Products AS Prod

     INNER JOIN dbo.Categories AS Cat

      ON Prod.CategoryId = Cat.CategoryId

     ORDER BY

      Cat.CategoryName

     COMPUTE SUM(Prod.UnitsInStock * Prod.UnitPrice) 

       BY Cat.CategoryName;

    SELECT

      Prod.ProductId ,

      Prod.ProductName ,

      Cat.CategoryName ,

      Prod.UnitsInStock * Prod.UnitPrice AS StockValue

     FROM dbo.Products AS Prod

     INNER JOIN dbo.Categories AS Cat

      ON Prod.CategoryId = Cat.CategoryId

     ORDER BY Cat.CategoryName

     COMPUTE SUM(Prod.UnitsInStock * Prod.UnitPrice)

       BY Cat.CategoryName

     COMPUTE SUM(Prod.UnitsInStock * Prod.UnitPrice);

    One more time.... Great article.

  • A very good explaination!

     

     


    Kindest Regards,

    Al Pagcaliwangan B.S. ECE, B.S.EE

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