Quick Tips: Adding Leading Zero to Integer Values (Padding) with DAX and Power Query

Quick Tips: Adding Leading Zero to Integer Values (Padding) with DAX and Power Query

There are some cases that we want to add a leading zero to a digit, such as showing 01 instead of 1, 02 instead of 2 and so on. We have two options to do this in Power BI, doing it in Power Query or doing it with DAX.

Adding a Leading Zero in Power Query

The first method is doing it in Power Query using the Text.PadStart() function.

Here is how the syntax of the function:

Text.PadStart(text as nullable text, count as number, optional character as nullable text)

And here is how the function works:

Text.PadStart(input string, the length of the string, an optional character to be added to the beginning of the string util we reach to the string length)

For example, Text.PadStart("12345", 10 , "a") returns aaaaa12345 and Text.PadStart("1", 2 , "0") returns 01.

Let’s create a list of integer values between 1 to 20 with the following expression:

{1..20}
Creating a List of Integer Values Between 1 to 20 In Power Query
Creating a List of Integer Values Between 1 to 20 In Power Query

Now we convert the list to a table by clicking the To Table button from the Transform tab:

Converting a List to a Table in Power Query
Converting a List to a Table in Power Query

Now we add a new column by clicking the Custom Column from the Add Column tab from the ribbon bar:

Adding a New Column to a Table in Power Query
Adding a New Custom Column to a Table in Power Query

Now we use the following expression in the Custom Column window to pad the numbers with a leading zero:

Continue reading “Quick Tips: Adding Leading Zero to Integer Values (Padding) with DAX and Power Query”

The Story of my Book, “Expert Data Modeling with Power BI”

Expert Data Modeling with Power BI
Expert Data Modeling with Power BI

In 2020, the world celebrated the new year with many uncertainties. Well, life is full of uncertainties, but, this one was very different. The world was facing a new pandemic that never experienced before. The first COVID19 case in New Zealand was confirmed in February 2020. In March 2020 the entire country went to lockdown for the first time. The world was experiencing a massive threat changing everyone’s lives. I was no different. Every day was starting with bad news. A relative passed away; a friend got the virus; the customers put the projects on hold etc. Nothing was looking normal anymore. You can’t even go to get a proper haircut, because everyone is in lockdown. This is me trying to smile after getting a homemade haircut. I bet many of you have done the same thing.

Soheil's Homemade Haircut
Soheil’s Homemade Haircut

One day, I checked my email and saw a message from Packt Publishing. They wanted to see if I am interested in writing a book about Power BI. That was a piece of good news after a long time. I always wanted to write a book about Power BI. Indeed, I attempted for the first time in 2016, but I couldn’t manage to get my ducks in a row to grasp the publishers’ attention.

I was not unfamiliar with writing books; indeed, I wrote my first book back in 2006 about Multimedia Applications in Persian. One of my passions in life is listening to music. And CDs were the most accessible music source with high-quality sound. I recall I saved money for some months, and I bought a Discman to listen to the music on the go. But CDs are rather bulky, and you could not have many of them in your pocket. So the next project was to save even more money to buy an MP3 player. But, converting Audio CDs to MP3 without compromising a lot on the sound quality was a real challenge for many people. And, that was my motive to write my first book in Persian to share my little knowledge with everyone. 

Continue reading “The Story of my Book, “Expert Data Modeling with Power BI””

Quick Tips: Renaming All Tables’ Columns in One Go in Power Query

Renaming All Tables' Columns in One Go in Power Query

I previously wrote a blog post explaining how to rename all columns in a table in one go with Power Query. One of my visitors raised a question in the comments about the possibility to rename all columns from all tables in one go. Interestingly enough, one of my customers had a similar requirement. So I thought it is good to write a Quick Tip explaining how to meet the requirement.

The Problem

You are connecting to the data sources from Power BI Desktop (or Excel or Data Flows). The columns of the source tables are not user friendly, so you require to rename all columns. You already know how to rename all columns of a table in one go but you’d like to apply the renaming columns patterns to all tables.

The Solution

The solution is quite simple. We require to connect to the source, but we do not navigate to any tables straight away. In my case, my source table is an on-premises SQL Server. So I connect to the SQL Server instance using the Sql.Database(Server, DB) function in Power Query where the Server and the DB are query parameters. Read more about query parameters here. The results would like the following image:

The Results of Sql.Database() Function in Power Query
The results of running the Sql.Database(Server, DB) function

As you see in the above image, the results include Tables, Views and Functions. We are not interested in Functions therefore we just filter them out. The following image shows the results after applying the filter:

Filtering out SQL Server Functions After Connecting from Power Query
Filtering out SQL Server Functions

If we look closer to the Data column, we see that the column is indeed a Structured Column. The structured values of the Data column are Table values. If we click on a cell (not on the Table value of the cell), we can see the actual underlying data, as shown in the following image:

Continue reading “Quick Tips: Renaming All Tables’ Columns in One Go in Power Query”

Finding Minimum Date and Maximum Date Across All Tables in Power Query in Power BI and Excel

Finding Minimum Date and Maximum Date Across All Tables in Power Query in Power BI and Excel

When we talk about data analysis in Power BI, creating a Date table is inevitable. There are different methods to create a Date table either in DAX or in Power Query. In DAX you my use either CALENDAR() function or CALENDARAUTO() function to create the Date table. In Power Query you may use a combination of List.Dates()#date() and #duration() functions. Either way, there is one point that is always challenging and it is how to find out a proper date range, starting from a date in the past and ending with a date in the future, that covers all relevant dates within the data model. One simple answer is, we can ask the business. The SMEs know what the valid date range is..

While this is a correct argument it is not always the case. Especially with the Start Date which is a date in the past. In many cases the business says:

Lets’s have a look at the data to find out.

That is also a correct point, we can always a look at the data, find all columns with either Date or DateTime datatypes then sort the data in ascending or descending order to get the results. But what if there many of them? Then this process can be very time consuming.

Many of you may already thought that we can use CALENDARAUTO() in DAX and we are good to go. Well, that’s not quite right. In many cases there are some Date or DateTime columns that must not be considered in our Date dimension. Like Birth Date or Deceased Date. More on this later in this post.

In this post I share a piece of code I wrote for myself. I was in a situation to identify the Start Date and the End Date of the date dimension many times, so I thought it might help you as well.

How it works?

The Power Query expressions I share in this post starts with getting all existing queries using:

  • #sections intrinsic variable
  • Filtering out the current query name, which is GetMinMaxAllDates in my sample, to avoid getting the following error:

Expression.Error: A cyclic reference was encountered during evaluation.

Expression.Error: A cyclic reference was encountered during evaluation.
Continue reading “Finding Minimum Date and Maximum Date Across All Tables in Power Query in Power BI and Excel”