Many to One relationships

[ysherriff]

Hi all,

I have a table titled “Marketing Assets” with many values for the column “Marketing Assets”. I have another table titled “Marketing Assets TopN” with only unique values for Marketing Assets.

I am wondering and need help to know why Power BI is not allowing me to make this a many to one relationship? It is forcing a Many to Many and I can’t do formulas accurately. Any help is appreciated.

[Greg_Deckler · Accepted solution]

@ysherriff I believe it should be One to Many, not Many to One. The order of your tables matters. The other possibility is that you have 2 items in your "unique" table that DAX does not consider unique. Remember that DAX is case insensitive so "A" is the same as "a" as far as DAX is concerned.

[ysherriff · Accepted solution]

I found the answer on Enterprise DNA forum:

"The reason why it’s forcing to create a “Many-to-Many Relationship” is because you’ve “NULL” values in both the sides of the table. Power BI is not able to distinguish the null value as a each unique value and therefore, it establishes or creates a “Many-to-Many Relationship” in this case."

Thank you.

[Greg_Deckler · Accepted solution]

@ysherriff I believe it should be One to Many, not Many to One. The order of your tables matters. The other possibility is that you have 2 items in your "unique" table that DAX does not consider unique. Remember that DAX is case insensitive so "A" is the same as "a" as far as DAX is concerned.