Slowly Changing Dimension (SCD) in Power BI, Part 2, Implementing SCD 1

Slowly Changing Dimension (SCD) in Power BI, Part 2, Implementing SCD 1

I explained what SCD means in a Business Intelligence solution in my previous post. We also discussed that while we do not expect to handle SCD2 in a Power BI implementation, we can handle scenarios similar to SCD1. In this post, I explain how to do so.

Scenario

We have a retail company selling products. The company releases the list of products in Excel format, including list price and dealer price, every year. The product list is released on the first day of July when the financial year starts. We have to implement a Power BI solution that keeps the latest product data to analyse the sales transactions. The following image shows the Product list for 2013:

Products List 2013 in Excel
Products List 2013

So each year, we receive a similar Excel file to the above image. The files are stored on a SharePoint Online site.

Scenario Explained

As the previous post explains, an SCD1 always keeps the current data by updating the old data with the new data. So an ETL process reads the data from the source, identifies the existing data in the destination table, inserts the new rows to the destination, updates the existing rows, and deletes the removed rows.

Here is why our scenario is similar to SCD1, with one exception:

  • We do not actually update the data in the Excel files and do not create an ETL process to read the data from the Excel files, identify the changes and apply the changes to an intermediary Excel file
  • We must read the data from the source Excel files, keep the latest data while filtering out the old ones and load the data into the data model.

As you see, while we are taking a very different implementation approach, the results are very similar with an exception: we do not delete any rows.

Implementation

Here is what we should do to achieve the goal:

  • We get the data in Power Query Editor using the SharePoint Folder connector
  • We combite the files
  • We use the ProductNumber column to identify the duplicated products
  • We use the Reporting Date column to identify the latest dates
  • We only keep the latest rows

Getting Data from SharePoint Online Folder

As we get the data from multiple files stored on SharePoint Online, we have to use the SharePoint Folder connector. Follow these steps:

  1. Login to SharePoint Online and navigate to the site holding the Product list Excel files and copy the site URL from the browser
Getting SharePoint Online Site URL
Getting SharePoint Online Site URL
  1. From the Get Data in the Power BI Desktop, select the SharePoint Folder connector
  2. Click Connect
Connecting to SharePoint Online Folder from Power BI
Connecting to SharePoint Online Folder from Power BI
  1. Paste the Site URL copied on step 1
  2. Click OK
Connecting to SharePoint Online Folder from Power BI using the SharePoint Folder connector
Connecting to SharePoint Online Folder from Power BI using the SharePoint Folder connector
  1. Click Transform Data
Transforming data in Power Query Editor
Transforming data in Power Query Editor
Continue reading “Slowly Changing Dimension (SCD) in Power BI, Part 2, Implementing SCD 1”

Combining X Number of Rows in Power Query for Power BI, Excel and Power Query Online

Combining X Number of Rows in Power Query for Power BI, Excel and Power Query Online

A while back, I was working on a project involving getting data from Excel files. The Excel files contain the data in sheets and tables. Getting the data from the tables is easy. However, the data in the sheets have some commentaries on top of the sheet, then the column names and then the data itself. Something like below:

Sample data
Sample data

This approach is pretty consistent across many Excel files. The customer wants to have the commentary in the column names when the data is imported into Power BI. So the final result must look like this:

Sample Data to be loaded into Power BI
Sample Data to be loaded into Power BI

The business requirement though is to combine the first 3 rows of data and promote it as the column name.

The Challenge

Let’s connect the Excel file and look at the data in Power BI Desktop.

Connecting to sample data from Power BI Desktop
Connecting to sample data from Power BI Desktop

As you can see in the preceding image, Power BI, or more precisely, Power Query, sees the data in Table format. After we click the Transform Data button, this is what we get in Power Query Editor:

Connected to sample data from Power Query in Power BI Desktop
Connected to sample data from Power Query in Power BI Desktop

We all know that tables consist of Columns and Rows. The conjunction of a column and a row is a Cell. What we require to do is to concatenate the values of cells from the first three rows. We also have to use a Space character to separate the values of each cell from the others.

Column, rows and cells in a Table in Power BI
Column, rows and cells in a Table

In Power Query, we can get each row of data in as a Record with the following syntax:

Table{RecordIndex}

In the above syntax, the Table can be the results of the previous transformation step, and the RecordIndex starts from 0. So to get the first row of the table in the preceding image, we use the following syntax:

#"Changed Type"{0}

Where the #"Changed Type" is the previous step. Here are the results of running the preceding expression:

Getting the first row of a Table
Getting the first row of a Table

So we can get the second and third rows with similar expressions. The following image shows the entire codes in the Advanced Editor:

Power Query expressions in Advanced Editor in Power BI Desktop
Power Query expressions in Advanced Editor

But how do we concatenate the values of the rows?

Continue reading “Combining X Number of Rows in Power Query for Power BI, Excel and Power Query Online”

Quick Tips: Conditionally Replace Values Based on Other Values in Power Query

Power Query (M) made a lot of data transformation activities much easier and value replacement is one of them. You can easily right click on any desired value in Power Query, either in Excel or Power BI, or other components of Power Platform in general, and simply replace that value with any desired alternative. Replacing values based on certain conditions however, may not seem that easy at first. I’ve seen a lot of Power Query (M) developers adding new columns to accomplish that. But adding a new column is not always a good idea, especially when you can do it in a simple single step in Power Query. In this post I show you a quick and easy way to that can help you handling many different value replacement scenarios.

Imagine you have a table like below and you have a requirement to replace the values column [B] with the values of column [C] if the [A] = [B].

Sample Data in Power BI

One way is to add a new conditional column and with the following logic:

if [B] = [A] then [C] else [B]

Well, it works perfectly fine, but wait, you’re adding a new column right? Wouldn’t it be better to handle the above simple scenario without adding a new column? If your answer is yes then continue reading.

Continue reading “Quick Tips: Conditionally Replace Values Based on Other Values in Power Query”

Quick Tips: How to Filter a Column by another Column from a Different Query in Power Query

Filter a Column by a Column from a Different Query in Power Query

A while ago I was visiting a customer that asked if they can filter a query data by a column from another query in Power BI. And I said of course you can. In this post I explain how that can be achieved in Power Query. The key point is to know how to reference a query and how to reference a column of that query in Power Query. This is useful when you have a lookup table that can be sourced from every supported data source in Power Query and you want to filter the results of another query by relevant column in the lookup query. In that case, you’ll have a sort of dynamic filtering. So, whenever you refresh your model if new records have been changed in or added to the source of the lookup query, your table will automatically include the new values in the filter step in Power Query.

Referencing a Query

It is quite simple, you just need to use the name of the query. If the query name contains special characters like space, then you need to wrap it with number sign and double quotes like #”QUERY_NAME”. So, if I want to reference another query, in a new blank query, then the Power Query (M) scripts would look like below:

let
    Source = Product
in
    Source

Or something like

let
    Source = #"Product Category"
in
    Source

Referencing a Column

Referencing a column is also quite simple. When you reference a column you need to mention the referencing query name, explained above, along with the column name in brackets. So, the format will look like #”QUERY_NAME”[COLUMN_NAME]. The result is a list of values of that particular column.

let
    Source = #"Product Category"[Product Category Name]
in
    Source
Referencing a Column from Another Query in Power Query
Continue reading “Quick Tips: How to Filter a Column by another Column from a Different Query in Power Query”