Getting the customerID on the Contact card

Hi, I am a bit lost, I want to get the customer ID on the contact card in the old 2.6 was it easy but now I can not find a field on in the table 5050, which is used to store the customer ID. Could someone help me please? thanks Kind regards, R.J. van Kuppeveld

If person then Customer ID is “On behalf of” if not then in relation table “Business relations” - where you can look it up or make sth. else.