Write a SQL query to show a table with columns Customer ID and Product ID of only products ordered by the customer and meets the following requirements:

a$.$ Customer ID should be included for all customers.

b$.$ Product ID included are only for products ordered by the customer with Customer ID in the first column.

c$.$ If the same customer has purchased the same product multiple times, the pair of Customer ID and Product ID should not be repeated.

Additional Notes:

$-$ Customer ID is used to uniquely identify each customer and is available as CustomerID in SALES$\_$ORDERS table as well as CustID in CUSTOMER table.

$-$ Product ID is used to uniquely identify each product and is available as ProductID in both PRODUCT and ORDER$\_$DETAILS tables.