Technology

In this post, I’ve documented a few Microsoft Power Query for Excel tips and tricks that I’ve learned from a recent project. For all of the following examples, I have an Excel table named TEST_DATA containing two columns (Description and Amount). The Power Query add-in for Excel can be downloaded from Microsoft.

Improving Performance

Ignore Privacy Level Settings

On the Power Query ribbon, click the Options button. The Query Options dialog box is displayed. Click the Privacy option, select Always ignore Privacy Level settings, and click the OK button.

Unless you have a specific reason to keep privacy settings active, you may gain some performance improvements by ignoring them. I didn’t notice much of an improvement, but it may depend on the volume and complexity of the data set involved.

Retrieve Source Data Once

When I started using Power Query, I created an initial query and then duplicated it each time I needed to start a new query. I would then modify the duplicated query to meet the new reporting requirement. All of these queries used the same source data which was a table on another worksheet. These weren’t complicated queries, but around the 15th query created in this manner, Power Query became sluggish during refreshes. The application would eventually throw Out of Memory exceptions and Excel would crash. The data source was a simple 100+ row worksheet in the same workbook. Again, nothing complicated.

Each of those queries started with a number of common steps, e.g. define the source data, remove some columns, and filter some data. After realizing my sloppiness, I defined a new query that handled all of these common steps. I then modified the existing queries to remove those common steps and instead refer to this base query as the starting point. Let’s assume that I named the base query as BASE_DATA. In each of the other queries, the source data is then established with the following statement: = #”BASE_DATA”

Once these common steps were pulled into a single, standalone connection query, then the Out of Memory exceptions stopped and the refreshes were substantially faster.

The BASE_DATA query is defined as:

Tips and Tricks

I’ve started a new query named EXAMPLE_QUERY to demonstrate the following tips and tricks. Again, it will use the TEST_DATA table data by way of the BASE_DATA query defined above.

Our first step is to establish the source data: = #”BASE_DATA”

Creating Total Rows

I know that a total row can be easily added to an Excel table through the standard Excel table options. However, what if we wanted to add one using Power Query? Through the Table.Combine and List.Sum functions we can combine all of the records from the source data with a calculated total row created using Table.FromRecords.

This step combines all of the rows from #”BASE_DATA” and, by using the Table.FromRecords function, creates an in-line table with one record. This in-line table sets the Description column to the text Total and the Amount column to the sum of all entries in the #”BASE_DATA”[Amount] column. I found this useful when creating a query where the base data was used in a waterfall / bridge chart.

Creating Running Totals

The next example adds a column to calculate a running or accumulating total for each of the rows. The first step is to create an Index column starting from zero. If you create an Index column starting from 1, then you would need to adjust the second step accordingly. The #”Create Total Row” is the name of the previous step.

Next, we add another column to contain the running total. Notice that #”BASE_DATA”[Amount] is used in the List.FirstN function. This is to avoid including the total row in the running total. If you used #”Added Index” (the default step name from adding the Index column), then the running total would incorrectly include the total row. Also, if you set your index to start at 1, then you would need to change the [Index]+1 parameter to [Index].

Using Data from the Previous Row

In this example, I create a new column that adds the value of the Amount column from the previous row to the value of the Amount column in the current row. The if conditional handles the first row (Index equals zero) where there is no previous row. This is for demonstration purposes only so the formula doesn’t particularly make sense to do in real life. The previous Amount column value is obtained with the statement #”Added Running Total”{[Index] – 1}[Amount].

Filtering Based on a Named Cell Value

Let’s say that you want to filter the data based on the value of a cell somewhere in your workbook. As the first step, you would need to define a named range for that cell. In this example, I’ll define a cell named FILTER_VALUE. To get the value of that cell from within a query, you can use a custom Power Query function which we’ll create called GetNamedCellValue. This query function has one parameter named rangeName and it is created as a connection only query.

Once defined, you can use this function in another query as follows:

Handling an Empty Table

Continuing with the same query, I add a filter to intentionally return an empty table to demonstrate this example. The source data doesn’t have any entries with an amount greater than 1,000 so I filter the column to show only entries with a greater amount.

If you’re using the custom GetNamedCellValue function defined earlier, you can set the FILTER_VALUE cell to 1,000 and use the following step instead:

As expected, the filter step returns an empty table. In the next step, I check if I have an empty table using Table.IsEmpty and then combine the empty table with an in-line table where the Description column is set to No entries found. If the table is not empty, I return the results from the previous step with no modification. I normally include this step at the end of most queries so that when a query is loaded to a worksheet, it is clear to users that the table is empty because of the data and not because of an error.

Summary

The full EXAMPLE_QUERY query used in the above examples is: