Index formula, duplicate records problem

I Need to know

how many unique corpid (column A) there are,
how many unique chainid (column b) there are,
how many unique externalid (column d) there are,

I also need to know how many externalid (column d) go in to chained (column b) and how many chained go into corpid (column A)


I have created something in access, which works okay, however i need it in excel

please find attached screen prints of access
unfortunately it wouldn’t allow me to attached the access file. But i have put it into excel so hopefully that it explains it abit better