Forum Discussion
Data Modelling Issue (Many to Many between Fact and Dimension)
Hello ,
Please help with the below data modelling question-
I have a fact table called purchase Order and few other dimensions connected in star schema . Now I have brought in a connection to smartsheet and the columns in both the fact and smart sheet table is as shown-
| Purchase Order Fact Table | ||
| Purchase Order | Line Number | Ordered Units |
| ABC1 | 1 | 4 |
| ABC1 | 2 | 5 |
| ABC1 | 3 | 2 |
| PQR2 | 1 | 13 |
| PQR2 | 2 | 24 |
| PQR2 | 3 | 5 |
| PQR2 | 4 | 1 |
| XYZ3 | 1 | 3 |
| XYZ3 | 2 | 8 |
| XYZ3 | 3 | 9 |
Smart Sheet Table-
| Program Code | Program Name | Purchase Order |
| 123 | united pgm | ABC1 |
| 345 | Exclusive pgm | ABC1 |
| 678 | Rep Pgm | PQR |
| 123 | united pgm | XYZ3 |
| 678 | Rep Pgm | XYZ3 |
- Purchase Order is the only common field(joining field) between both the fact and smart sheet table.
- One purchase order in Smart sheet table could belong to more than 1 program and hence can have more than one program code. This results in a M-M relationship as shown in table above(Multiple records of purchase order).
- In the Power BI report , Purchase order Number is used for display from Fact table and only 'Program Code' and 'Program Name' is used from Smartsheet table.
Problem - I tried single and bi-directional filter for the M-M relationship between these two tables they are not yielding right results. Even if I create a bridging table it would have one purchase order occuring twice because of the program codes.
Please advise how fix this data model issue.
Hi,
try creating a bridge/factless fact table it will solve your many to many relationship problem.
if your don't know about bridge/factless fact table you can search on google that how to build one and what are the use cases of it.I hope this is helpfull
thank you
3 Replies
Hi,
try creating a bridge/factless fact table it will solve your many to many relationship problem.
if your don't know about bridge/factless fact table you can search on google that how to build one and what are the use cases of it.I hope this is helpfull
thank you
That is not a Purchase Order Fact Table. It is a PO Line Item fact table. Add a PO dimension table in between.
Hi , Thank you all for responding. A bridge table did not resolve it. I went with a M-M bi-directional join and enabled the 'show items with no data' so this gave me the expected results of a left outer join by bringing in only the program codes of the Purchase order used from fact.
