2 Replies Latest reply: Dec 1, 2016 6:15 AM by laxman V RSS

    Star Schema

    laxman V

      hi,

      i have a data in Excel file of around 30 fields,

      i created multiple excel sheets with the help of those 30 fields and formed a star schema,

       

      here the problem is when i am preparing an app with the star schema it showing diff values copared to app with the excel fie with 30 fields.

       

      can anyone let me know why it is happening and also let me know the way yo avoid it.

       

      i am attaching the files have a look at it

       

      Gettingstartdata is the whole data file and remaining are the tables divided from the original one to prepare star schema.

        • Re: Star Schema
          Arnaldo Sandoval

          Hi Iaxman,

           

          You did not elaborate on what kind of problem you are facing, just that you are getting different results. Here my notes based on the information you provided.

           

          Product Details:

          • It is not a product dimension because its lines are associated with the transactions.
          • I created a Products dimension by picking up just all your products: 77 products.
          • I did not used the Product Details as products already have an id in the GettingStartedData.

           

          Cust Details:

          • This is not a dimension, you have duplicated records.
          • Created a Customers dimension by removing all the duplicated records: 90 customers.

           

          Sales Data:

          • The information here contains sales-cost figures per product per quarter.
          • It is not related to the Orders fact table in your model.
          • I created a dimension named Product_Sales
          • This table does not contain a year, only quarters, so the best we could do with is to show products sales per quater.


          Main:

          • This table seems to contains your Orders fact table.
          • It exposes the ProductID and CustomerID columns which is fine.
          • This table does not contains measures, no orders details, the best way to get any measure is by joining with the product details on the transactions id, but, this will not fit well with the start mode.

           

          Order Details:

          • This table contains the Quantity measure, and the OrderID.
          • If we look at the OrderID = 10248, it contains 3 rows with 3 different quantities. We could assume this order contains 3 products, but there is not direct way to know the products involved.

           

          Info:

          • This table add very little value to the model, actually by containing year and status, there is very little we could do with these fields.

           

          Your star schema is not properly defined, it does not allow us to put together Order-Product-Quanty, and without a measure, it will be difficult for Qlik to produce meaningful results.

           

          Hope this helps,