As indicated in the Entity Framework image below, I have 3 tables, tblModel, tblModelFetish and tblFetish. A record in tblModel can have multiple records in the tblModelFetish table linked by the modelid column. The tblModelFetish table links to the tblFetish table via the fetishID column to get the fetish description stored in the fetish column. This Entity Model was generated with VS 2010 from an existing database including foreign keys.
a Entity Data Model http://spreadthenudes.com/efmodel.jpg
Using the odata syntax, I'm able to access all models (http://localhost:51157/WcfDataService.svc/tblModels) or a specific model (http://localhost:51157/WcfDataService.svc/tblModels(11)) successfully. I'm having trouble accessing the related tables data via odata, I've tried many permutations including expand etc.
What I want is a result set of all the columns in the tblModel and the related tblFetish records including the fetish column from the tblFetish table. In other words, Mary (a modelname in tableModel) has 3 fetishes (3 records in tblModelFetish) named beach, travel and coffee (stored in tblFetish, fetish column).
What is the odata syntax to acquire this?
thanks for reading! Bob
Try either:
http://localhost:51157/WcfDataService.svc/tblModels(11)?$expand=tblModelFetishes/tblFetish
or
http://localhost:51157/WcfDataService.svc/tblModels?$filter=id eq 11&$expand=tblModelFetishes/tblFetish
Just to make it clear you will not get one huge result set with all columns but the entity graph consisted of your entities.
Related
I have two fact tables: FactSales & FactInvoices. Both have an foreign key relationship with DimDate.Datekey. In VS, the SSAS DSV displays these relationships (the lines are drawn between the tables).
In the DSV I decided to to create a named query that limits the dimdate to 2021. After doing this, I still see the relationships between the two fact tables and dimdate (which is now a named query).
At the DB-level, I created a 3rd fact table called FactExpenses. FactExpenses also has an FK relationship with DimDate.Datekey. The problem is that my dsv (in SSAS) does not recognize this relationship (ie. It doesn't draw the line between both tables).
Two questions: why doesn't VS display the relationship between my 3rd fact table with the named query but it does with the other two fact tables? I understand that the relationship isn't with the named query, but the relationship should disappear in all the fact tables.
When I want to limit the amount of data displayed in dimdate, should I use a named query?
The relationships in the DSV are separate to the foreign keys on the base tables, but they get added automatically based on the database schema when you add tables to the DSV. My guess would be when you added the initial dim and fact tables to the DSV in Visual Studio it automatically added the relationships based on the foreign keys that exist on the base tables, but this may not occur automatically for named queries. You can manually add the relationship yourself for the third table to get the same result.
I think a named query is a reasonable approach for the filtering you want to do. An alternative would be to create a view in the source database if you need to do more intense or complex filtering.
Context:
I am creating a dashboard in Excel based on the data model I am building in Power Pivot. The source data in the data model is based on various other excel tables I am regularly receiving and copy-pasting into my workbook (their incoming structure is out of my control). My goal is to perform all data processing within Power Pivot/DAX rather than manipulating the data in the worksheets before loading into the model.
Problem:
In my model, I have a table (tabCases) which includes status updates on all cases from a management system. This table has a column named case-ID (not unique). I need to create a lookup-table with unique case-id's where I can create new columns with various KPIs for each case.
How can I do this in Power Pivot?
I found two suggestions in this article but none of them work for me (opt. 1 because it requires a manual creation of the unique ID list and opt. 2 because I don't have a database access).
In my mind there should be something really simple I could do, such as i.e.:
Add new table to data model
Set first column to be equal to DISTINCT(tabCases[caseID])
Is there such a way?
A Linkback Table might help you. Please see the link below:
https://www.sqlbi.com/articles/linkback-tables-in-powerpivot-for-excel-2013/
Thanks
I have searched on the net but was not able to get an answer for my case. I am migrating a project on doctrine.
What is the correct way to link an entity to another entity that contains all the "families" of a project.
The families can be for instance :
"project_status" : status1, status2, status3
"countries" : en, us, cn ...
"tags" : tag1, tag2, ...
So all these values are stored in the same table in database and my entity handle this.
So now i have an entity that can have for example several countries or tags.
In the database i have one text field for the countries and one text field for the tags. And i store the ids of each tag or family inside these fields.
So let's say that I have one entity called "family" and one entity called "myEntity".
What is the best way to do ?
Ok maybe I have found one way in fact.
Instead of using my usual text field in my entity table to store the ids of the families I will use a join table.
So let's say that I have one table with my different lists in my project (country, file_status, and other possible lists). I will then have one entity for this table "familyEntity".
I will create a table that will be used for the cases in which one entityA can have several values of the same family (country for instance). In that case, I wil have a many to many association between familyEntity and entityA for that family.
If I have another entityB that uses the family "status" with several values possible, I will also have a many to many association using the same table for the association.
In the other cases in which only one value is possible for one family I will have many to one association.
Don't know if it is the right way but it occured to me that way. This solution seems ok for primary keys that are not compound).
I am using Database First EF to generate model from the existing database. When I first generated the models, it ignores only one of the table, the entity was not added to EDMX, no model file is created for the table and no context is created for the entity.
When I tried to explicitly add the table to EDMX (when generating the model, selected the specific table first and then updated the model with all the other tables from the database), it complained with the following error.
Two entities with possibly different keys are mapped to the same row. Ensure these two mapping fragments map both ends of the AssociationSet to the corresponding columns.
This specific table has two columns which are primary keys of some other tables and both the columns are specified as Primary keys for the table.
Am I doing something wrong or should I handle this table differently since it has two columns defined as Primary Keys? Any suggestions greatly appreciated!
You are not doing anything wrong. Your table is junction table for many-to-many relation. You don't need that table in the model because EF (in contrast to database) can handle many-to-many relation directly without any intermediate. The table is actually mapped on behind of the many-to-many relation - you will see that in mapping details window.
Btw. you are not using code first. Code first = no EDMX.
we have requirement like below :
For each customer will upload different files having different columns, column names are different from one client to another client and change in the number columns also.
For that one we will stored all the details in one table like
column1,column2,column3 ...........columnN
And will store column mapping some other table
First name=column1
Second Name=Column2
like this, up to this is ok ,but if we are using entity framework how stronly types will work in this case.
In the front end will show the combox box which will display all the client and we will show the data in the grid
Here is important thing is we have to show the End user column name instead our column name like column1,column2
Out put sholud be like below
Combox box ---- Client name
Grid
First name Second Name
---------------------------------
Harish Kumar
EF is not good choice for this type of application. It will map exactly what you have in database - one big entity with Column1, Column2, etc. properties and one entity with properties like ColumnName, PropertyName. That is all because EF doesn't support advanced data driven mapping.
Your UI / logic will need some logic to correctly interpret these data and moreover it will also have to correctly transform user input and actions back to EF understandable form.
Imho using EF for this is overhead, use ADO.NET directly. Also check SharePoint because it has this already implemented.