What is the difference between addcolumns and selectcolumns in DAX?

[SandipGhosh]

Hi, We all know that both addcolumns and selectcolumns have almost the same syntax and return a table, but I want to know that

What is the difference between addcolumns and selectcolumns in DAX? is there any example for that?

[garythomannCoGC]

Create a subset of the table in Power BI and add calculations using SELECTCOLUMNS DAX Function 

And further the above article makes it all very clear :}

[amitchandak · Accepted solution]

@SandipGhosh , In case, addcolumn, exiting column are already selected and you add post that. The column that are there in table part of the addcolumn.

Selectcolumn is select each column/formula with a new name. There is nothing selected beforehand.

[SandipGhosh]

Hi,

Can you writeen the reply in english please.

[Pragati11]

Hi @SandipGhosh ,

• ADDCOLUMNS allows you to add new calculated columns in an existing table.
• SELECTCOLUMNS allows you to select columns from an original table, without starting with the defined structure of the original table

You can refer following links on details on both of these DAX functions:

https://docs.microsoft.com/en-us/dax/addcolumns-function-dax

https://docs.microsoft.com/en-us/dax/selectcolumns-function-dax

In addition in the below blog, it is shown how SELECTCOLUMNS can be a representation of ADDCOLUMNS and SUMMARIZE functions:

https://blog.crossjoin.co.uk/2015/06/01/using-selectcolumns-to-alias-columns-in-dax/

Thanks,

Pragati

[lkalawski]

Hi @SandipGhosh ,

This is explained in the Remarks section:  https://dax.guide/selectcolumns/

Please check it.

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[SandipGhosh]

Hi,

it stated that "SELECTCOLUMNS starts with an empty table before adding columns." I dont understand what does it mean?

Can you explain me that?