What value is returned when RELATED finds no match?

[macfuller]

I must have fallen asleep in DAX 101, but I have a tough time testing for RELATED() values that aren't there.

Example: We order products that may be substituted by our vendor. We subsequently have to revise our PO to change from the vendor item ID in our item master to the one provided by our vendor. We retain our internal PeopleSoft number "PS ID" regardless of the item. Not all orders ("scripted") have PeopleSoft numbers/items in our item master however. Therefore I would like to return 3 values into a "Sub" column of our Orders table:

"Scripted" - no matching value found in our item master.
"Sub" = Orders[Vendor ID] <> RELATED('Item Master'[Supplier ID']
"Base" = Orders[Vendor ID] = RELATED('Item Master'[Supplier ID']

the item master table has a relationship via the [PS ID] field to the Orders table.

I'm not clear on whether I test for BLANK() or null string for the Scripted response, or if I have to do a FILTER statement somewhere.

 

[ParamRay]

Hello, the RELATED() function returns BLANK() if there is no matching row in the parent table. You can test for it using the ISBLANK() function.

 

[macfuller]

That doesn't work for me. It doesn't trap for the error.
=ISBLANK(RELATED('Item Master'[Vendor Item ID])) returns FALSE for items I know are missing in the lookup table.

=RELATED('Item Master'[Vendor Item ID]) = "" also returns FALSE

I don't know what type of value is being returned

 

[SyedUsman]

That doesn't work for me. It doesn't trap for the error.
=ISBLANK(RELATED('Item Master'[Vendor Item ID])) returns FALSE for items I know are missing in the lookup table.

=RELATED('Item Master'[Vendor Item ID]) = "" also returns FALSE

I don't know what type of value is being returned

Related returns a blank when the lookup value is not found . how ever to check the blank use the next column with ISBLANK & not the same column in which related also resides.

 

[akice]

Here is an article to better understand BLANK() in DAX:

https://www.sqlbi.com/articles/blank-handling-in-dax/