What is the point of DummyVariable = null?

[Nietzsche]

Hello everybody, 

I am reading the book Master Microsoft Power BI 2nd ed, in the book there is this code and the author don't really explain why there is a need for DummyVariable = null after defining the Source.

Can someone tell me why the author used DummyVariable = null?

Thank you.

[lbendlin · Accepted solution]

To demonstrate the lazy vs eager evaluation logic of Power Query?

Evaluation model - PowerQuery M | Microsoft Learn

[v-jingzhan-msft · Accepted solution]

Hi @Nietzsche 

Based on my understanding, "DummyVariable = null" is not a need after the Source. Probably the author is to show that it can be added here. And when it is added here, it will not affect the DirectQuery table as it is not used thus is ignored. 

Best Regards,
Jing
If this post helps, please Accept it as Solution to help other members find it. Appreciate your Kudos!

[lbendlin · Accepted solution]

To demonstrate the lazy vs eager evaluation logic of Power Query?

Evaluation model - PowerQuery M | Microsoft Learn