One to Many Association

The following example illustrates creation of a one-to-many association within an Entity Framework model.

The database contains the Dept and Emp tables, which have a foreign key constraint between them.

The field DEPTNO in the table Emp receives the ID value of the associated record in the Dept table.

images_Association1toMany-table

We perform the following sequence of operations:

create an Entity Framework Core model;
add the Dept and Emp tables to the model.

As a result, we have the following model:

images_Association1toMany-model-TDA

The association between the Dept and the Emp entities looks as follows:

images_Association-Editor-1ToMany-EFC

 In case all foreign key columns of the details table are nullable, the association will have the zero-or-one to many type, which means that the detail class navigation property referring to the master class can be NULL.

 

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