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sandra1
Level: Powered On

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

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?



2 REPLIES 2
Community Support Team
Community Support Team

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

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"

1212.PNG

 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,

 

Community Support Team _ Phoebe Liu
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.
sandra1
Level: Powered On

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

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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