How to search on one column and then count distinct entries in another column (Excel)

[Rachel1994]

I am trying to compare sales data from two tables. The first table shows product info (Location, product code etc.), and the second table shows all transaction data (Location, product code, customer info for each transaction).

I want to look at each product+location in the first table, then find all instances of it in the second table, and count the number of distinct customers 

Example data:

Product Data Table

Location	Product Code	Description
Location A	Product 1	Car
Location B	Product 1	Car
Location A	Product 2	Bike
Location B	Product 2	Bike

Order Data Table

Location	Product Code	Order number	Customer
Location A	Product 1	01234	Customer X
Location A	Product 1	01235	Customer X
Location A	Product 1	01236	Customer Y
Location A	Product 2	01237	Customer X
Location B	Product 1	01238	Customer X

In this example,  I want to know the number of distinct customers who ordered Product 1 from Location A, which is 2.

I would appreciate any help I can get!

[#2]

@Rachel1994 

=COUNTA(UNIQUE(FILTER($I$2:$I$6,$G$2:$G$6=A9)))

Maybe with this formula for the layout of the attached file. 

[#3]

@Rachel1994 

Slightly modified formula suggested by @OliverScheurich if use structured tables

which is

=LET(
  f,  FILTER(
         Orders[Customer],
        ( Orders[Location] = [@Location] ) *
        ( Orders[Product Code] = [@[Product Code]] ) ),
  COUNTA( UNIQUE( f ) ) )

[#4]

@Rachel1994 

in E3:

=LET(
    filtered, FILTER(OrderData[Customer],
                     (OrderData[Location]=[@Location]) *
                     (OrderData[Product Code]=[@[Product Code]]),
                     0
    ),
    IF(COUNT(filtered), 0, COUNTA(UNIQUE(filtered)))
)

[#5]

Thanks so much for your help, this worked perfectly!