For each client, get in every row, a column containing first purchase date

Question

I am using Power BI (I can use only DAX).

Starting from this table:

Client	Purchase Date
ClientA	01/01/2023
ClientA	01/02/2023
ClientB	01/03/2023
ClientB	01/02/2023

I would like to create a new column, called First Purchase Date that, for each client, keeps first purchase date, like:

Client	Purchase Date	First Purchase Date
Client A	01/01/2023	01/01/2023
Client A	01/02/2023	01/01/2023
Client B	01/03/2023	01/02/2023
Client B	01/02/2023	01/02/2023

How can I solve it using only DAX?

I tried to create

First Purchase Date = MINX(VALUES(Table1[Client]),MIN(Table2[Purchase Date]))

But it's like Third column is equal to second:

Client	Purchase Date	First Purchase Date
Client A	01/01/2023	01/01/2023
Client A	01/02/2023	01/02/2023
Client B	01/03/2023	01/03/2023
Client B	01/02/2023	01/02/2023

Answer 1

REMOVEFILTERS to remove the row context.

Try:

First Purchase Date =
  CALCULATE(
    MIN(Table2[Purchase Date]),
    REMOVEFILTERS(Table2[Purchase Date])
  )

Answer 2

You can try this below DAX for New Column-

First Purchase Date = 
CALCULATE(
    MIN(your_table_name[Purchase Date]),
    ALLEXCEPT(your_table_name, your_table_name[Client])
)