I need to create a table with the first log, given some conditions

[ScripTeapot_]

Hellor

I need some help with this problem: I have many users and each one has made, at least, one purchase at some point, I need to know the date of the first purchase they have made to count the amount of first purchaces made in a month.

OG table

User	purchase_date
A	2023-02-01
A	2023-02-14
A	2023-03-29
B	2023-02-10
C	2022-12-23
C	2023-07-04
C	2023-09-15

First purchase table

user	"first_purchase"
A	2023-02-01
B	2023-02-10
C	2022-12-23

Probably this is not the best way to do this, if someone can guide me to something I can study to achieve this goal is very appreciated.

[DataNinja777 · Accepted solution]

Hi @ScripTeapot_ 

You can produce your required output by the following table dax formula.

In this simple data model, I separately created a calendar table (dimension table) and created a one to many relationship with the fact table because it is the best practice to do so.   

I omit detailed explanations here, but instead, please find attached the link to the pbix file, and please let me know if anything is unclear.

First purchase table.pbix