Handling null in one-to-many relationship

[sebastien_druon]

Hello

I have 2 simple tables with what I would expect to be a 1 to many relationship.

Problem 1

PowerBI however imposes a many-to-many relationship

Here are the table contents, the "Customers" table containing a null value:

How can I avoid powerbi creating a many-to-many relationship?

Problem 2

I created a simple table visual to display the number of tickets per customer.

I would expect Customer A and Customer B to appear, with a count of 0 for Customer A.

PowerBI does not display Customer A at all though

How can I solve that issue?

Many thanks!

PS: a copy of the pbix file here:

https://1drv.ms/u/s!AsdHsyy8cIM4jcAt62ZodGYi0CHMqw?e=WXeP7B

[BrennoBBS]

Was going crazy and creating a new related table with Dax just because it wasn't showing null values.

This info: "You need to enable the option "show items with no data" of filed "Data"" saved my life, thank you so much sir! 🙂

[v-easonf-msft · Accepted solution]

Hi, @sebastien_druon 

#1  The cardinality type selected  in relationship depends on the data in the tables("SystemID"  contains blank value).If you force a one-to-many relationship between tables, the following error will be reported.

As a workaround, you can change the type of column 'SystemID' from "whole number" to 'Text'.

#2 
You need to enable the option "show items with no data" of filed "Data"

You can also directly create a new measure 'Count of ticket' to replace the original field"ticket" as below:

Count of ticket = COUNT(Tickets[Ticket])+0

Please  check my sample pbix file for more details.

Best Regards,
Community Support Team _ Eason
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.

[Ashish_Mathur]

Hi,

Create a third table which should list down all the unique ID's (without blanks).  Now connect the ID columns of the 2 tables to this third table.  Create a Many to One relationship wth cardinality of Single.