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Editorial Team
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Asked: 2026-05-17T02:21:35+00:00

Is it possible to have table per type inheritance in the Entity Framework 4

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Is it possible to have “table per type” inheritance in the Entity Framework 4 if the derived table has a composite primary key?

Here is my table setup:

TABLE: ConfigurationKey (Base Entity)
PK: Id

TABLE: ConfigurationKey_Device (Derived Entity)
PK: ConfigurationKeyId (FK to ConfigurationKey.Id)
PK: DeviceId (FK to Device.Id)

For what it’s worth, ConfigurationKey is going to be abstract and other types are going to derive from ConfigurationKey.

Using the EF designer, I have:

  • Added the inheritance rule
  • Deleted ConfigurationKeyId from ConfigurationKey_Device
  • Deleted the FK linking ConfigurationKey_Device to ConfigurationKey
  • Updated the mapping of the ConfigurationKey_Device.ConfigurationKeyId column to the inherited Id property.

The error I am now getting is:

Error 3003: Problem in mapping
fragments starting at line xxx:All the
key properties (ConfigurationKeys.Id)
of the EntitySet ConfigurationKeys
must be mapped to all the key
properties
(ConfigurationKey_Device.ConfigurationKeyId,
ConfigurationKey_Device.DeviceId) of
table ConfigurationKey_Device.

Thanks,
Chris

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1 Answer

  1. Editorial Team

    The error message answers to your question itself.
    You are actually trying to inherit from an entity with one-column key with an entity with two-column key.
    It seems the better solution will be either to have a ComplexType enclosing the common set of properties, or a common interface implementing the necessary functionality.

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