Create row id in a custom table

[profilewatercli]

I have a custom table and custom column as below.

The following column is what im want the output to be

how do i use dax to do this?

[v-yaningy-msft · Accepted solution]

Hi, @profilewatercli 

Thanks for @PowerBigginer help. If you want to create a Index column by DAX, you can refer to following method.

DAX:

Index = RANKX(ALL('Table'), 'Table'[Exam Session], , DESC, Dense)

Best Regards,
Yang
Community Support Team

If there is any post helps, then please consider Accept it as the solution to help the other members find it more quickly.
If I misunderstand your needs or you still have problems on it, please feel free to let us know. Thanks a lot!

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[PowerBigginer]

Go to Power query (Right click on the table click Edit Option) then add Index column 

For more Power BI tips and Tricks 
https://powertipstricks.blogspot.com/ check out the blog
If this post helps Please Mark as a solution

[profilewatercli]

Is there a way to do this using dax?