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    copied!<p>I've tried defining the following tables: </p> <ul> <li>Orders [Id (primary, identity), ClientName, FriendlyOrderNum (unique)]</li> <li>OrderItems [Id (primary, identity), FriendlyOrderNum (unique), ItemName]</li> </ul> <p>And a foreign key mapping from OrderItems.FriendlyOrderNum (Mant) to Orders.FriendlyOrderNum (one).</p> <p>If unique non-primary keys are possible the following SSDL should work:</p> <pre><code>&lt;Schema Namespace="EfUkFk_DbModel.Store" Alias="Self" Provider="System.Data.SqlClient" ProviderManifestToken="2008" xmlns:store="http://schemas.microsoft.com/ado/2007/12/edm/EntityStoreSchemaGenerator" xmlns="http://schemas.microsoft.com/ado/2009/02/edm/ssdl"&gt; &lt;EntityContainer Name="EfUkFk_DbModelStoreContainer"&gt; &lt;EntitySet Name="OrderItems" EntityType="EfUkFk_DbModel.Store.OrderItems" store:Type="Tables" Schema="dbo" /&gt; &lt;EntitySet Name="Orders" EntityType="EfUkFk_DbModel.Store.Orders" store:Type="Tables" Schema="dbo" /&gt; &lt;/EntityContainer&gt; &lt;EntityType Name="OrderItems"&gt; &lt;Key&gt; &lt;PropertyRef Name="RowId" /&gt; &lt;/Key&gt; &lt;Property Name="RowId" Type="bigint" Nullable="false" StoreGeneratedPattern="Identity" /&gt; &lt;Property Name="OrderNum" Type="char" Nullable="false" MaxLength="5" /&gt; &lt;Property Name="ItemName" Type="varchar" MaxLength="100" /&gt; &lt;/EntityType&gt; &lt;!--Errors Found During Generation: warning 6035: The relationship 'FK_OrderItems_Orders' has columns that are not part of the key of the table on the primary side of the relationship. The relationship was excluded. --&gt; &lt;EntityType Name="Orders"&gt; &lt;Key&gt; &lt;PropertyRef Name="RowId" /&gt; &lt;/Key&gt; &lt;Property Name="RowId" Type="bigint" Nullable="false" StoreGeneratedPattern="Identity" /&gt; &lt;Property Name="ClientName" Type="varchar" MaxLength="100" /&gt; &lt;Property Name="OrderNum" Type="char" Nullable="false" MaxLength="5" /&gt; &lt;/EntityType&gt; &lt;!-- AsafR --&gt; &lt;Association Name="FK_OrderItems_Orders"&gt; &lt;End Role="Orders" Type="EfUkFk_DbModel.Store.Orders" Multiplicity="1"&gt; &lt;/End&gt; &lt;End Role="OrderItems" Type="EfUkFk_DbModel.Store.OrderItems" Multiplicity="*" /&gt; &lt;ReferentialConstraint&gt; &lt;Principal Role="Orders"&gt; &lt;PropertyRef Name="OrderNum" /&gt; &lt;/Principal&gt; &lt;Dependent Role="OrderItems"&gt; &lt;PropertyRef Name="OrderNum" /&gt; &lt;/Dependent&gt; &lt;/ReferentialConstraint&gt; &lt;/Association&gt; &lt;/Schema&gt;&lt;/edmx:StorageModels&gt; </code></pre> <p>It doesn't. There's also no possibility for adding more &lt;key&gt; elements in an &lt;EntityType&gt;.</p> <p>My conclusion is that non-primary unique keys are not support in EF 4. </p>
 

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