%META:TOPICPARENT{name="VirtProgressEntityFrameworkUsage"}% ===Manually creating EDM Associations (FKs) for the Progress isports database=== The following steps will detail what is required to manually create **Associations** in your Entity Data Model. You will need to determine where these associations exist and their multiplicity (one-to-one, one-to-many, etc.) before commencing with the following steps. NOTE: These steps will need to be repeated for each association. 1. The first Association I will deal with is the relationship between Customer and Invoice, identified by the presence of the scalar property Cust_Num in both entities. This is a one-to-many relationship, as a Customer may have any number of Invoices. %BR%%BR%

%BR%%BR% 2. To add the Association, right click on the Customer entity, then **Add** -> **Association**. %BR%%BR%

%BR%%BR% 3. You will now see the **Add Association** dialog. %BR%%BR%

%BR%%BR% 4. For this association, the only thing that needs changing is the default name assigned to the **Navigation Property**. Change the default from Invoice to invoices on the Customer end of the association.%BR%%BR%This better reflects the multiplicity of the association such that a Customer is associated with zero or many Invoices (plural). %BR%%BR%

%BR%%BR%Typically, here is where you will -%BR%%BR% * Select the entity at each end of the association * Select the multiplicity of each end of the association, and * Provide suitable names for the association and its navigation properties%BR%%BR% 5. Hit **OK**. The diagram will be refreshed to include the newly created association. %BR%%BR%

%BR%%BR% 6. You now need to edit the mappings associated with the newly created association, so right-click the association on the diagram. Then, select **Table Mapping** to display the **Mapping Details** pane. %BR%%BR%

%BR%%BR% 7. Click the line which reads <Add a Table or View> to reveal a drop down list of all entities. %BR%%BR%

%BR%%BR% 8. Here you need to select the entity on the right/far side of the association (the entity where the foreign key exists).%BR%%BR%In this example, it is the Invoice entity. %BR%%BR%

%BR%%BR% 9. The **Mapping Details** pane now refreshes to display both ends of the association. Now, you must provide relevant target store data types in the **Column** column for the key fields, as depicted here. %BR%%BR%

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%BR%%BR% 10. Once the mapping is complete, you can build the project using **Build** -> **Build Solution**. NOTE: It is worthwhile building as each association is made, since the error messages can be a little confusing. %BR%%BR%

%BR%%BR% 11. This should result in the following error, which is included here since I (the author) found it misleading. %BR%%BR%

%BR%%BR% This error indicates that there are two source columns — in this case, the Invoice entity's Scalar Property Cust_Num and Navigation Property Customer — which are both mapped to the same target column — the Progress column Invoice.Cust_Num — and this is not supported. %BR%%BR%

%BR%%BR% 12. The solution is simple! Simply delete the mapping of the Scalar Property Invoice.Cust_Num. Its only purpose is to hold data representing a relationship/association (it is a Foreign Key), which has already been represented by the newly created association and resulting Navigation Property Customer.%BR%%BR% Right click on Invoice.Cust_Num then **Delete**. %BR%%BR%

%BR%%BR% 13. The model diagram will refresh to reflect this change. %BR%%BR%

%BR%%BR% 14. Build the project, again, using **Build** -> **Build Solution**. %BR%%BR%

%BR%%BR% 15. The project should now build fine. %BR%%BR%

%BR%%BR% You will need to repeat these steps for each association, until you have a completed Entity Data Model. %BR%%BR%

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