Power Query: Refer to a Column by Name Stored as a Text Parameter (REDUX)

Power Query is a powerful tool in Microsoft Excel that allows you to import, transform, and analyze data from various sources. One common task in Power Query is referencing a column by its name, which is stored as a text parameter. In this article, we will explore how to achieve this using Power Query's REDUX feature.

Before we dive into the details, let's first understand the problem we are trying to solve. Imagine you have a dataset with multiple columns, and you want to perform some operations on a specific column. However, the name of the column is not fixed and may change from time to time. In such cases, referencing the column by its name becomes a challenge.

To overcome this challenge, we can use Power Query's REDUX feature. REDUX stands for "Refer to a Column by Name Stored as a Text Parameter." It allows us to dynamically reference a column by its name, even if the name changes.

To demonstrate how to use REDUX, let's consider a simple example. Suppose we have a dataset with three columns: "Product ID," "Product Name," and "Price." We want to perform some calculations on the "Price" column, but we don't know if the column name will remain the same in the future. Here's how we can achieve this using Power Query:

First, we need to load the dataset into Power Query. Go to the "Data" tab in Excel and click on "From Table/Range." Select the range containing your dataset and click "OK." This will open the Power Query Editor, where we can perform various transformations on the data.

In the Power Query Editor, we can see a preview of our dataset. To reference the "Price" column dynamically, we need to create a parameter that stores the column name as text. To do this, go to the "Home" tab and click on "Manage Parameters" in the "External Data" group.

In the "Manage Parameters" dialog box, click on "New" to create a new parameter. Give it a name, such as "ColumnName," and set the data type to "Text." Enter the default column name, in this case, "Price," and click "OK."

Now that we have created the parameter, we can use it to reference the column dynamically. Go back to the Power Query Editor and select the column where we want to perform calculations, in this case, the "Price" column. Right-click on the column header and choose "Insert Custom Column" from the context menu.

In the "Insert Custom Column" dialog box, enter a name for the new column, such as "Calculated Price." Now, here comes the magic of REDUX. Instead of entering a static formula, we can use the parameter we created earlier to reference the column dynamically. To do this, enter the following formula in the "Custom column formula" field:

In the formula above, "#"" refers to the previous step in the Power Query Editor, and "ColumnName" refers to the parameter we created earlier. By concatenating the "#" with the value of the parameter, we can dynamically reference the column by its name.

Once you have entered the formula, click "OK" to create the custom column. You will see a new column added to your dataset with the name "Calculated Price." This column will contain the same values as the dynamically referenced column, in this case, the "Price" column.

Now, you can perform any calculations or transformations on the "Calculated Price" column, just like any other column in your dataset. The best part is that even if the column name changes in the future, you can simply update the parameter value, and the custom column will automatically reflect the changes.

In conclusion, Power Query's REDUX feature allows us to dynamically reference a column by its name, even if the name changes. By creating a parameter and using it in a custom column formula, we can achieve this flexibility and avoid hard-coding column names. This is particularly useful when working with datasets that have dynamic column structures.

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