A Power Query Custom Function to Rename all Columns at Once in a Table

A Power Query Custom Function to Rename all Columns at Once in a Table

I am involved with a Power BI development in the past few days. I got some data exported from various systems in different formats, including Excel, CSV and OData. The CSV files are data export dumps from an ERP system. Working with ERP systems can be very time consuming, especially when you don’t have access to the data model, and you get the data in raw format in CSV files. It is challenging, as in the ERP systems, the table names and column names are not user friendly at all, which makes sense. The ERP systems are being used in various environments for many different customers with different requirements. So if we can get our hands to the underlying data model, we see configuration tables keeping column names. Some of the columns are custom built to cover specific needs. The tables may have many columns that are not necessarily useful for analytical purposes. So it is quite critical to have a good understanding of the underlying entity model. Anyhow, I don’t want to go off-topic.

The Problem

So, here is my scenario. I received about 10 files, including 15 tables. Some tables are quite small, so I didn’t bother. But some of them are really wide like having between 150 to 208 columns. Nice!

Looking at the column names, they cannot be more difficult to read than they are, and I have multiple tables like that. So I have to rename those columns to something more readable, more on this side of the story later.

Background

I emailed back to my customer, asking for their help. Luckily they have a very nice data expert who also understands their ERP system as well as the underlying entity model. I emailed him all the current column names and asked if he can provide more user-friendly names. He replied me back with a mapping table in Excel. Here is an example to show the Column Names Mapping table:

Column Names Mapping

I was quite happy with the mapping table. Now, the next step is to rename all columns is based on the mapping table. Ouch! I have almost 800 columns to rename. That is literally a pain in the neck, and it doesn’t sound quite right to burn the project time to rename 800 columns.

But wait, what about writing automating the rename process? Like writing a custom function to rename all columns at once? I recall I read an excellent blog post about renaming multiple columns in Power Query that Gilbert Quevauvilliers wrote in 2018. I definitely recommend looking at his blog post. So I must do something similar to what Gilbert did; creating a custom function that gets the original columns names and brings back the new names. Then I use the custom function in each table to rename the columns. Easy!

Continue reading “A Power Query Custom Function to Rename all Columns at Once in a Table”

Quick Tips, Power BI Desktop, Query Parameters, Part 4, Passing Power Query Parameter Values to SQL Server Stored Procedures

I have written 3 blogposts about query parameters in the past.

This is the fourth one in the form of Quick Tips. Here is the scenario. One of my customers had a requirement to get data from a Stored Procedure from SQL Server. She required to pass the values from a Query Parameter back to SQL Server and get the results in Power BI.

The solution is somewhat easy. I created a simple stored procedure in AdventureWorksDW2019 as below:

CREATE PROCEDURE SP_Sales_by_Date 
	@date int
AS
BEGIN
	SET NOCOUNT ON;
	SELECT *
	FROM [dbo].[FactInternetSales]
	WHERE OrderDateKey >= @date
END
GO

In Power BI Desktop, get data from SQL Server, then:

  • Enter Server name
  • Enter Database name
  • Select Data Connectivity Mode
  • Expand the Advanced options
  • Type in a SQL statement to call the stored procedure like below:
exec SP_Sales_by_Date @date = 20140101
  • Click OK
Get Data From SQL Server using SQL Statements in Power BI Desktop
  • Click Transform Data
Transform Data in Power BI Desktop

Now we need to create a Query Parameter. In my sample I create a DateKey in Decimal Number data type:

Creating New Query Parameter in Power BI Desktop
Continue reading “Quick Tips, Power BI Desktop, Query Parameters, Part 4, Passing Power Query Parameter Values to SQL Server Stored Procedures”

Quick Tips: Converting Hexadecimal, Oct and Binary to Decimal in a Single Power Query Function

A Power Query Function to Convert HEX, OCT and BIN values to DEC

A while ago I wrote a blogpost on how to use Unicode characters in Power BI. In that blogpost I used a recursive Power Query function to convert Hex values to Dec values. A few weeks back one of my site visitors kindly shared his non-recursive version of Power Query function which beautifully does the job. A big shout out to Rocco Lupoi for sharing his code. So, I decided to share it with everyone so more people can leverage his nice Power Query function. I have touched his code a bit though, but it was more of a cosmetic change, so all credits of this blogpost goes to Rocco. The benefits of his code is not limited to being non-recursive. The code below converts numbers of any base when the base is smaller than 16 like Binary and Oct, so it is not limited to Hex values only. The other benefit of the below code is that it is not case sensitive (note to the digits step on the code below).

Here is the fnHex2Dec function for Power Query:

(input as text, optional base as number) as number =>
let
        values = [
                0=0,
                1=1,
                2=2,
                3=3,
                4=4,
                5=5,
                6=6,
                7=7,
                8=8,
                9=9,
                A=10,
                B=11,
                C=12,
                D=13,
                E=14,
                F=15
        ],
        digits = Text.ToList(Text.Upper(input)),
        dim = List.Count(digits)-1,
        exp = if base=null then 16 else base,
        Result = List.Sum(
                        List.Transform(
                                {0..dim}
                                , each Record.Field(values, digits{_}) * Number.Power(exp, dim - _)
                                )
                        )
in
        Result

As you see in the code above, the base parameter is optional, so if not provided base 16 would be the default.

This is how we can invoke the above function:

fnHex2Dec("AbCdEf", null)
Invoking fnHex2Dec function to convert numbers of any base to decimal
Continue reading “Quick Tips: Converting Hexadecimal, Oct and Binary to Decimal in a Single Power Query Function”

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”