COLUMN THAT AFFECT ROWS INDIVIDUALLY.

Good day everyone,

I'd like to know if is possible to create a column that affect every row individually?

For example. i need to calculate a column with the exchange rate of USD in my country but it tends to vary frequenly so that's why i make this discussion. I know that by typing the current value of the exchange rate i can reach this setting but as i want to make it a calculated field i need to know if is possible by affecting the rows individually.