How to add formulate calculated field

Hi guys,

I would like to add a new attribute to the llx_commande table. In the “additional attributes” tab I can define a formula but I dont know how.

The idea is that I would like an extra column in the llv_commande table with the delivery week number (WEEK() function value between 1-53) derived from the column ‘date_livraison’

Any help would be much appreciated!

Greets
Andreas