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A Energy Question Customized Perform to Rename all Columns at As soon as in a Desk

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

I’m concerned with a Energy BI improvement previously few days. I received some information exported from numerous techniques in several codecs, together with Excel, CSV and OData. The CSV recordsdata are information export dumps from an ERP system. Working with ERP techniques will be very time consuming, particularly if you don’t have entry to the information mannequin, and also you get the information in uncooked format in CSV recordsdata. It’s difficult, as within the ERP techniques, the desk names and column names will not be person pleasant in any respect, which is sensible. The ERP techniques are being utilized in numerous environments for a lot of totally different prospects with totally different necessities. So if we are able to get our arms to the underlying information mannequin, we see configuration tables conserving column names. A number of the columns are customized constructed to cowl particular wants. The tables could have many columns that aren’t essentially helpful for analytical functions. So it’s fairly important to have understanding of the underlying entity mannequin. Anyhow, I don’t need to go off-topic.

The Downside

So, right here is my situation. I obtained about 10 recordsdata, together with 15 tables. Some tables are fairly small, so I didn’t hassle. However a few of them are actually huge like having between 150 to 208 columns. Good!

Wanting on the column names, they can’t be tougher to learn than they’re, and I’ve a number of tables like that. So I’ve to rename these columns to one thing extra readable, extra on this aspect of the story later.


I emailed again to my buyer, asking for his or her assist. Fortunately they’ve a really good information knowledgeable who additionally understands their ERP system in addition to the underlying entity mannequin. I emailed him all the present column names and requested if he can present extra user-friendly names. He replied me again with a mapping desk in Excel. Right here is an instance to point out the Column Names Mapping desk:

Column Names Mapping

I used to be fairly proud of the mapping desk. Now, the following step is to rename all columns is predicated on the mapping desk. Ouch! I’ve nearly 800 columns to rename. That’s actually a ache within the neck, and it doesn’t sound fairly proper to burn the venture time to rename 800 columns.

However wait, what about writing automating the rename course of? Like writing a customized perform to rename all columns without delay? I recall I learn a superb weblog submit about renaming a number of columns in Energy Question that Gilbert Quevauvilliers wrote in 2018. I undoubtedly advocate taking a look at his weblog submit. So I need to do one thing just like what Gilbert did; making a customized perform that will get the unique columns names and brings again the brand new names. Then I exploit the customized perform in every desk to rename the columns. Simple!

The Resolution

Earlier than we begin, I have to have my mapping desk in Energy BI. So I create a brand new desk utilizing the Enter Knowledge performance. Then I copy the information from my mapping desk and paste it into the brand new desk. I identify the brand new desk Column Names Mapping. The primary motive to make use of the Enter Knowledge performance as a substitute of getting information immediately from the file (in my case an Excel file) is that if for any motive sooner or later we miss the mapping file, the perform under can’t discover the columns to map. Therefore, it brings again the unique column names. This implies if we created an information mannequin on prime of the brand new column names, then the entire mannequin breaks, which isn’t any good. I additionally disable load on the Column Names Mapping question as I don’t have to have it in my information mannequin.

Creating fnRenameColumnsFromRefQuery Customized Perform

The perform reads via the Column Names Mapping desk and renames the columns of the question that we invoked the perform in when it finds the matching. If it doesn’t discover the matching, it leaves the column identify is. Right here you go, that is the perform I got here up with.

(ColumnName as textual content) as textual content =>
    Supply = 
        if (
                "Column Names Mapping"
             ) = true 
        then #"Column Names Mapping" 
        else null,
    ColumnNewName = 
            if Record.Incorporates(Supply[Column Name], ColumnName) = true 
                if Textual content.Trim(Desk.SelectRows(Supply, every ([Column Name] = ColumnName)){0}[Description]) = "" 
                then ColumnName 
                else Desk.SelectRows(Supply, every ([Column Name] = ColumnName)){0}[Description] 
            else Supply 
        in any other case ColumnName

You’ll be able to obtain the previous expressions from right here.

Right here is the way it works:

  • The fnRenameColumnsFromRefQuery accepts a ColumnName parameter as textual content and the output of the perform is a textual content.
  • The Supply step checks the existence of a Column Names Mapping question. The Column Names Mapping is the mapping tables proven within the previous picture that holds the unique column names and their mapping. It’s possible you’ll use a distinct identify of selection. If the Column Names Mapping question exists then Supply = #"Column Names Mappings" else Supply = null
  • The ColumnNewName step checks the contents of the Supply step which is both the Column Names Mapping desk or a null. If it’s the Column Names Mapping desk then it seems for the ColumnName parameter within the [Column Name] column throughout the Column Names Mapping desk. If it finds the matching worth then it makes use of the ColumnName parameter to filters the [Column Name]. Then it will get the corresponding worth from the [Description] column which accommodates the brand new column identify, in any other case it brings the unique column identify again

The final step is to make use of the fnRenameColumnsFromRefQuery customized perform to rename the desk’s columns.

Invoking the fnRenameColumnsFromRefQuery Customized Perform

Energy Question has a perform to renamed column names in tables which is the Desk.TransformColumnNames(desk as desk, NameGenerator as perform) perform. The Desk.TransformColumnNames() perform accepts a NameGenerator as its second operand. So we are able to use our customized perform because the second operand throughout the Desk.TransformColumnNames() perform to rename all columns. The ultimate code should appear to be this:

Desk.TransformColumnNames(PREVIOUS_STEP_NAME, fnRenameColumnsFromRefQuery)

Right here is an screenshot of the column names earlier than and after renaming the columns:

Renaming columns using a reference list in Power Query
Renaming columns utilizing a reference listing in Energy Question

You’ll be able to obtain the PBIX pattern right here.


If we predict what we’re doing is kind of laborious and we’re burning a variety of venture time doing that, it’s good to consider a technique to automate the job. It’d look a bit advanced, complicated and time-consuming at first, however consider me in lots of instances it value it and after you discover the best way you should utilize it in lots of different related eventualities which saves you a variety of time. Having stated that, there isn’t a assure that we are able to automate our situation, so we might be higher to be ready for it. For example, it’s a very long time that I’m pondering to automate the method of renaming all queries showing within the Question Editor, however I’m but to discover a answer for it. Right here is the problem, in some instances, we connect with the information supply, and now we have many tables to be loaded to the mannequin, and the desk names will not be at all times person pleasant. It’s just like renaming columns however on the question degree. So in case you already know the answer, please share it with the group so everybody can profit out of your efforts. On the finish of the day, we study from one another. So sharing our information is a paying ahead to the following individual.

The opposite level is to at all times bear in mind to ask different specialists for assist. We could be knowledgeable in some areas however it’s unimaginable for somebody being knowledgeable in every little thing. Like in my case the client had an knowledgeable who offered me the column names mapping desk, with out his assist I couldn’t get the job finished.

As at all times, I might love know your opinion, so please share your ideas within the remark part under.



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