Power Query - Add column from related table

[MichaelF1]

Hi everyone, 

I'm trying to add a column from one related table to another in Power Query.

So in table 1 I have:

ID	Cust_Ref	Cust_PostCode
1	Customer001	AB21 4EF
2	Customer002	BC65 R56
3	Customer003	CD32 Y76

And in table 2 I have

ID	Cust_Ref	Contact_Name
1	Customer001	Dave
2	Customer002	Dee
3	Customer003	Dozy

I want to add the Cust_PostCode column from table 1 to table 2, matching Cust_Ref from both tables, so table 2 has 4 columns.

I know how to do this using Merge Queries but this seems to take a very large amount of processing power, so I need to find another way if possible.

Thanks in advance 🙂

Michael

[luohen · Accepted solution]

Hi @MichaelF1 ,

You can achieve it by the following methods:
1. Power Query: Add a custom column as below in Table2

= Table.AddColumn(#"Changed Type", "Cust_PostCode", each Table1[Cust_PostCode]{List.PositionOf(Table1[Cust_Ref],[Cust_Ref])})

In addition, you can refer the following blog to achieve it, there are two methods(merge method and add a custom column method) include in this blog.

VLOOKUP in Power Query Using List Functions

Merge method

Add a custom column method

2. DAX: Create a calculated column as below to get it

Column = 
CALCULATE (
    MAX ( 'Table1'[Cust_PostCode] ),
    FILTER ( 'Table1', 'Table1'[Cust_Ref] = 'Table2'[Cust_Ref] )
)

Best Regards

[luohen · Accepted solution]

Hi @MichaelF1 ,

You can achieve it by the following methods:
1. Power Query: Add a custom column as below in Table2

= Table.AddColumn(#"Changed Type", "Cust_PostCode", each Table1[Cust_PostCode]{List.PositionOf(Table1[Cust_Ref],[Cust_Ref])})

In addition, you can refer the following blog to achieve it, there are two methods(merge method and add a custom column method) include in this blog.

VLOOKUP in Power Query Using List Functions

Merge method

Add a custom column method

2. DAX: Create a calculated column as below to get it

Column = 
CALCULATE (
    MAX ( 'Table1'[Cust_PostCode] ),
    FILTER ( 'Table1', 'Table1'[Cust_Ref] = 'Table2'[Cust_Ref] )
)

Best Regards

[MichaelF1]

Thank you very much, I didn't know about the add column method, I'll check it out 🙂

[luohen · Accepted solution]

Hi @MichaelF1 ,

You can download my sample pbix file from this link to get more details about creating custom column in Power Query Editor...

Add a custom column in Power BI Desktop

Best Regards

[MichaelF1]

Thanks @luohen , that's very helpful 🙂

[amitchandak]

@MichaelF1 , In power query you have to use merge .

In DAX you can use related or relatedtable with maxx or sumx etc

refer 4 ways to copy data from one table to another
https://www.youtube.com/watch?v=Wu1mWxR23jU
https://www.youtube.com/watch?v=czNHt7UXIe8

[MichaelF1]

Hi @amitchandak ,

Thank you for the reply. I was hoping to do it in PQ rather than DAX. My problem is that I keep getting the 'resources exceed' error in Power BI so I was hoping to shift some of the heavy lifting to PQ, but Merge seems unworkable due to the length of tiome it takes.

Do you by any chance have any tips or links to improving the performance of DAX measures?

Thanks again,

Michael

[amitchandak]

@MichaelF1 , My viewpoint is, that if data is large do not do it in power bi. Bring it from the source.

But try the same in dataflow on service.  Try merge there