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CDS many-to-many relationship and joining tables that have no relationship

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Posted on by sandra1

Hello,

I'm trying to create some entities in CDS for my existing database schema to use it in model-driven applications. I want to do it from scratch (and not use the "Get Data" option).

Here are my questions:

Question 1:

I have modeled a many-to-many relationship between entity A and entity B. But I don't know how to insert data for this relationship because I don't have a form or view for it. (Normally I would think that a third entity is created with the relationship name).

How can you get/insert data for this relationship?

Question 2:

I also want to create a view that contains data from more than one table, even if the tables have no direct relationship.

So I would join the tables in SQL, but when I want to create a view in CDS, I can only select related fields.

For example, I have a "likes" table with the data:

Person A; Person B;

Anna; Peter

Peter; Anna

Mike; Peter

Anna; Mike

and only want to get rows where people like each other (output should be Anna, Peter; Peter).

How to create such a view with CDS?

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Microsoft Dataverse with Power Apps

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v-yutliu-msft on at

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Hi @sandra1 ,

Q1:

Do you want to know how to update entity that has many-to--many relationship?

Since in entity that has many-to--many relationship, there is no lookup field.

So you could update it very easily.

1)update it in powerapps

create an app connected with this entity, use collect/patch function to update

2)update it by clicking "edit data in excel"/"get data"

3)use data integration to import data to this entity

Here's a doc about how to make this:

https://docs.microsoft.com/en-us/power-platform/admin/data-integrator

Q2:

I'm afraid it's not supported to create view in CDS currently.

I suggest you express your views about adding this function on PowerApps Ideas Forum. Your precious feedback will be very helpful for our work.

https://powerusers.microsoft.com/t5/PowerApps-Ideas/idb-p/PowerAppsIdeas

If you insist in using view, I suggest you try SQLServer.

You could display data of view in SQL Server. (can not write)

Best regards,

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sandra1 39 on at

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Hello @v-yutliu-msft,
Thank you very much for your answer.

To question 1:
Sorry, I don't think I expressed myself very well. I know that I can write data for Entity A and Entity B in the tables. (and I can do that with "get data/gedit data in excel" etc.)
But when I model a many-to-many relationship, I usually want to know which entry of realisation A has a partner in relation B.
For example, a book can be written by more than one author and an author can write more than one book.
So I thought if I created a many-to-many relationship in CDS, it would create a new entity (table) "written by" for that relationship, where I could write down who wrote a book. But that's not the case (correct me if I'm wrong). So where can I store the information "wirtten by"? Is the solution to create a third entity "wirtten by" with two many-to-one relationships to author and book? But if that's the case, I do not know in which case I should use a many-to-many relationship?

You are also sad :
"So you can easily update it.
1) update it in powerapps
Create an app associated with this entity using the Collect/Patch function."
The Collect and Patch functions are not available for model-driven apps. Is that correct?

To question 2:
You recommend using the SQL Server. They are only supported by canvas applications, aren't they?

Thanks in advance

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SimoneBuscaino 2 on at

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Hello to all,

I've got the same problem.

I created two entities to link together with a many-to-many relationship, normally I would think of a third table where it is possible to link the two records of the two tables, but in this case it seems not to be.

Can anyone help us?

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MkKhan 4 on at

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@SimoneBuscaino The third table is basically not visible in the portal, it is created and maintained by CDS/Dataserve. You will just use relate and unrelate feature to associate and remove that association.

"With Many-to-many relationships a Relationship (or Intersect) table stores the data that associates the tables. This table has a One-to-many table relationship with both of the related tables and only stores the necessary values to define the relationship. You can’t add custom columns to a relationship table and it is never visible in the user interface."
View this documentation https://docs.microsoft.com/en-us/powerapps/maker/data-platform/create-edit-nn-relationships

Also this for relate and unrelate and further details on relationship
https://docs.microsoft.com/en-us/powerapps/maker/canvas-apps/functions/function-relate-unrelate

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Fubar 8,338 Super User 2025 Season 2 on at

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There are 2 types of many-to-many relationships,
One is 'automatic' where you explicitly choose to create a many-to-many. In this case in the background the link entity/table is created and contains the GIUDs of the records at both ends of the relationship. In the automatic one you cannot add additional attributes/columns to it - it is just to link not contain additional data.
The other is 'manual' where you create the intersect entity i.e. another entity/table that has a lookup to entity/table A and another lookup to entity/table B. As you create the intersect, you can add additional attributes/columns.
Key benefit of the automatic is that it is quick to setup (and at least in the Model Driven apps, not 100% sure with a Canvas app) you don't have to do anything else - it just works. The downside is that there are limitations such as you can't add additional Columns.

For loading initial data into an automatic many-to-many you can also look at XrmToolBox, there is a plugin for that tool that allows you to populate the automatic intersect entity (can use the GUID or text) e.g. you create a file that contains the pairs of GUIDs for the records at the end of the relationships, and import that file.

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