Many to Many Relationship

Question

In powerpivot we are facing problem in resolving the many-to-many relationship between tables.
Current table schema is:
Having 4 tables-
Bills - columns are- Bill No(primary key)
Billing Fee Table-Fee ID(primary key), Bill Type, Sub Bill Type
FeeList Table-FeeList ID(primary key),Fee ID(Foriegn Key to Billingble),
Bill No(Foriegn Key to Bills)
Payments Table-Pay ID(Primary Key), Bill No(Foriegn Key to Bills)
Bills is the primary table for Feelist Table
and Payments Table -Bill No is the primary key.
Billing Fee Table is primary table for FeeList Table -
Fee ID is the primary key.
To create a pivot table using Payments Table, I need
Bill Type and Sub Bill Type. Hence fetched from
Biling Fee Table to FeeList Table based on the
Fee ID column using RELATED function.
As FeeList Table and Payments Table is having duplicate
Bill Nos, it is not possible to get Bill Type and
Sub Bill Type to Payments Table. I am trying to use LOOKUPVALUE
function to get data based on the Bill No, as there is no direct relationship exists between these two tables.
I have tried using
=LOOKUPVALUE('FeeList Table'[Sub Bill Type], 'FeeList Table'[Bill No], 'Payments Table'[Bill No]) function. But
the lookupvalue function returns an error if a duplicate is found.
Error is as below:
Calculation error in column 'Payments Table'[Sub Bill Type]: A table of multiple values was supplied where a single value was expected.
Kindly assist to resolve this issue.
Thanks

Answer 1

Hi Rekha,
What should your LOOKUPVALUE return if multiple rows are found in the FeeListTable? By the way it should work if a really finds "duplicates" (i.e. multiple times the same return value) but fails if it returns multiple rows with different values.
If you for example would want to return the first entry that was found, you could try (have not checked in PP for typos):
CALCULATE(MIN('FeeList Table'[Sub Bill Type]),
  FILTER('FeeList Table',
     'FeeList Table'[Bill No] = 'Payments Table'[Bill No]
Edit: a very nice way to handle Many-to-Many relationships is explained here:
http://blog.gbrueckl.at/2012/05/resolving-many-to-many-relationships-leveraging-dax-cross-table-filtering/
Julian Wissel | BI for NAV @ http://en.navbi.com | Blog @ blog.navida.eu