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SSDL Specification

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Note

SSDL v1 is unsupported, please update to V3

Store schema definition language (SSDL) is an XML-based language that describes the storage model of an Entity Framework application.

In an Entity Framework application, storage model metadata is loaded from a .ssdl file (written in SSDL) into an instance of the System.Data.Metadata.Edm.StoreItemCollection and is accessible by using methods in the System.Data.Metadata.Edm.MetadataWorkspace class. Entity Framework uses storage model metadata to translate queries against the conceptual model to store-specific commands.

The Entity Framework Designer (EF Designer) stores storage model information in an .edmx file at design time. At build time the Entity Designer uses information in an .edmx file to create the .ssdl file that is needed by Entity Framework at runtime.

Versions of SSDL are differentiated by XML namespaces.

SSDL Version XML Namespace
SSDL v1 https://schemas.microsoft.com/ado/2006/04/edm/ssdl
SSDL v2 https://schemas.microsoft.com/ado/2009/02/edm/ssdl
SSDL v3 https://schemas.microsoft.com/ado/2009/11/edm/ssdl

Association Element (SSDL)

An Association element in store schema definition language (SSDL) specifies table columns that participate in a foreign key constraint in the underlying database. Two required child End elements specify tables at the ends of the association and the multiplicity at each end. An optional ReferentialConstraint element specifies the principal and dependent ends of the association as well as the participating columns. If no ReferentialConstraint element is present, an AssociationSetMapping element must be used to specify the column mappings for the association.

The Association element can have the following child elements (in the order listed):

  • Documentation (zero or one)
  • End (exactly two)
  • ReferentialConstraint (zero or one)
  • Annotation elements (zero or more)

Applicable Attributes

The following table describes the attributes that can be applied to the Association element.

Attribute Name Is Required Value
Name Yes The name of the corresponding foreign key constraint in the underlying database.

Note

Any number of annotation attributes (custom XML attributes) may be applied to the Association element. However, custom attributes may not belong to any XML namespace that is reserved for SSDL. The fully-qualified names for any two custom attributes cannot be the same.

Example

The following example shows an Association element that uses a ReferentialConstraint element to specify the columns that participate in the FK_CustomerOrders foreign key constraint:

 <Association Name="FK_CustomerOrders">
   <End Role="Customers"
        Type="ExampleModel.Store.Customers" Multiplicity="1">
     <OnDelete Action="Cascade" />
   </End>
   <End Role="Orders"
        Type="ExampleModel.Store.Orders" Multiplicity="*" />
   <ReferentialConstraint>
     <Principal Role="Customers">
       <PropertyRef Name="CustomerId" />
     </Principal>
     <Dependent Role="Orders">
       <PropertyRef Name="CustomerId" />
     </Dependent>
   </ReferentialConstraint>
 </Association>

AssociationSet Element (SSDL)

The AssociationSet element in store schema definition language (SSDL) represents a foreign key constraint between two tables in the underlying database. The table columns that participate in the foreign key constraint are specified in an Association element. The Association element that corresponds to a given AssociationSet element is specified in the Association attribute of the AssociationSet element.

SSDL association sets are mapped to CSDL association sets by an AssociationSetMapping element. However, if the CSDL association for a given CSDL association set is defined by using a ReferentialConstraint element , no corresponding AssociationSetMapping element is necessary. In this case, if an AssociationSetMapping element is present, the mappings it defines will be overridden by the ReferentialConstraint element.

The AssociationSet element can have the following child elements (in the order listed):

  • Documentation (zero or one)
  • End (zero or two)
  • Annotation elements (zero or more)

Applicable Attributes

The following table describes the attributes that can be applied to the AssociationSet element.

Attribute Name Is Required Value
Name Yes The name of the foreign key constraint that the association set represents.
Association Yes The name of the association that defines the columns that participate in the foreign key constraint.

Note

Any number of annotation attributes (custom XML attributes) may be applied to the AssociationSet element. However, custom attributes may not belong to any XML namespace that is reserved for SSDL. The fully-qualified names for any two custom attributes cannot be the same.

Example

The following example shows an AssociationSet element that represents the FK_CustomerOrders foreign key constraint in the underlying database:

 <AssociationSet Name="FK_CustomerOrders"
                 Association="ExampleModel.Store.FK_CustomerOrders">
   <End Role="Customers" EntitySet="Customers" />
   <End Role="Orders" EntitySet="Orders" />
 </AssociationSet>

CollectionType Element (SSDL)

The CollectionType element in store schema definition language (SSDL) specifies that a function’s return type is a collection. The CollectionType element is a child of the ReturnType element. The type of collection is specified by using the RowType child element:

Note

Any number of annotation attributes (custom XML attributes) may be applied to the CollectionType element. However, custom attributes may not belong to any XML namespace that is reserved for SSDL. The fully-qualified names for any two custom attributes cannot be the same.

Example

The following example shows a function that uses a CollectionType element to specify that the function returns a collection of rows.

   <Function Name="GetProducts" IsComposable="true" Schema="dbo">
     <ReturnType>
       <CollectionType>
         <RowType>
           <Property Name="ProductID" Type="int" Nullable="false" />
           <Property Name="CategoryID" Type="bigint" Nullable="false" />
           <Property Name="ProductName" Type="nvarchar" MaxLength="40" Nullable="false" />
           <Property Name="UnitPrice" Type="money" />
           <Property Name="Discontinued" Type="bit" />
         </RowType>
       </CollectionType>
     </ReturnType>
   </Function>

CommandText Element (SSDL)

The CommandText element in store schema definition language (SSDL) is a child of the Function element that allows you to define a SQL statement that is executed at the database. The CommandText element allows you to add functionality that is similar to a stored procedure in the database, but you define the CommandText element in the storage model.

The CommandText element cannot have child elements. The body of the CommandText element must be a valid SQL statement for the underlying database.

No attributes are applicable to the CommandText element.

Example

The following example shows a Function element with a child CommandText element. Expose the UpdateProductInOrder function as a method on the ObjectContext by importing it into the conceptual model.  

 <Function Name="UpdateProductInOrder" IsComposable="false">
   <CommandText>
     UPDATE Orders
     SET ProductId = @productId
     WHERE OrderId = @orderId;
   </CommandText>
   <Parameter Name="productId"
              Mode="In"
              Type="int"/>
   <Parameter Name="orderId"
              Mode="In"
              Type="int"/>
 </Function>

DefiningQuery Element (SSDL)

The DefiningQuery element in store schema definition language (SSDL) allows you to execute a SQL statement directly in the underlying database. The DefiningQuery element is commonly used like a database view, but the view is defined in the storage model instead of the database. The view defined in a DefiningQuery element can be mapped to an entity type in the conceptual model through an EntitySetMapping element. These mappings are read-only.  

The following SSDL syntax shows the declaration of an EntitySet followed by the DefiningQuery element that contains a query used to retrieve the view.

 <Schema>
     <EntitySet Name="Tables" EntityType="Self.STable">
         <DefiningQuery>
           SELECT  TABLE_CATALOG,
                   'test' as TABLE_SCHEMA,
                   TABLE_NAME
           FROM    INFORMATION_SCHEMA.TABLES
         </DefiningQuery>
     </EntitySet>
 </Schema>

You can use stored procedures in the Entity Framework to enable read-write scenarios over views. You can use either a data source view or an Entity SQL view as the base table for retrieving data and for change processing by stored procedures.

You can use the DefiningQuery element to target Microsoft SQL Server Compact 3.5. Though SQL Server Compact 3.5 does not support stored procedures, you can implement similar functionality with the DefiningQuery element. Another place where it can be useful is in creating stored procedures to overcome a mismatch between the data types used in the programming language and those of the data source. You could write a DefiningQuery that takes a certain set of parameters and then calls a stored procedure with a different set of parameters, for example, a stored procedure that deletes data.

Dependent Element (SSDL)

The Dependent element in store schema definition language (SSDL) is a child element to the ReferentialConstraint element that defines the dependent end of a foreign key constraint (also called a referential constraint). The Dependent element specifies the column (or columns) in a table that reference a primary key column (or columns). PropertyRef elements specify which columns are referenced. The Principal element specifies the primary key columns that are referenced by columns that are specified in the Dependent element.

The Dependent element can have the following child elements (in the order listed):

  • PropertyRef (one or more)
  • Annotation elements (zero or more)

Applicable Attributes

The following table describes the attributes that can be applied to the Dependent element.

Attribute Name Is Required Value
Role Yes The same value as the Role attribute (if used) of the corresponding End element; otherwise, the name of the table that contains the referencing column.

Note

Any number of annotation attributes (custom XML attributes) may be applied to the Dependent element. However, custom attributes may not belong to any XML namespace that is reserved for CSDL. The fully-qualified names for any two custom attributes cannot be the same.

Example

The following example shows an Association element that uses a ReferentialConstraint element to specify the columns that participate in the FK_CustomerOrders foreign key constraint. The Dependent element specifies the CustomerId column of the Order table as the dependent end of the constraint.

 <Association Name="FK_CustomerOrders">
   <End Role="Customers"
        Type="ExampleModel.Store.Customers" Multiplicity="1">
     <OnDelete Action="Cascade" />
   </End>
   <End Role="Orders"
        Type="ExampleModel.Store.Orders" Multiplicity="*" />
   <ReferentialConstraint>
     <Principal Role="Customers">
       <PropertyRef Name="CustomerId" />
     </Principal>
     <Dependent Role="Orders">
       <PropertyRef Name="CustomerId" />
     </Dependent>
   </ReferentialConstraint>
 </Association>

Documentation Element (SSDL)

The Documentation element in store schema definition language (SSDL) can be used to provide information about an object that is defined in a parent element.

The Documentation element can have the following child elements (in the order listed):

  • Summary: A brief description of the parent element. (zero or one element)
  • LongDescription: An extensive description of the parent element. (zero or one element)

Applicable Attributes

Any number of annotation attributes (custom XML attributes) may be applied to the Documentation element. However, custom attributes may not belong to any XML namespace that is reserved for CSDL. The fully-qualified names for any two custom attributes cannot be the same.

Example

The following example shows the Documentation element as a child element of an EntityType element.

 <EntityType Name="Customers">
   <Documentation>
     <Summary>Summary here.</Summary>
     <LongDescription>Long description here.</LongDescription>
   </Documentation>
   <Key>
     <PropertyRef Name="CustomerId" />
   </Key>
   <Property Name="CustomerId" Type="int" Nullable="false" />
   <Property Name="Name" Type="nvarchar(max)" Nullable="false" />
 </EntityType>

End Element (SSDL)

The End element in store schema definition language (SSDL) specifies the table and number of rows at one end of a foreign key constraint in the underlying database. The End element can be a child of the Association element or the AssociationSet element. In each case, the possible child elements and applicable attributes are different.

End Element as a Child of the Association Element

An End element (as a child of the Association element) specifies the table and number of rows at the end of a foreign key constraint with the Type and Multiplicity attributes respectively. Ends of a foreign key constraint are defined as part of an SSDL association; an SSDL association must have exactly two ends.

An End element can have the following child elements (in the order listed):

  • Documentation (zero or one element)
  • OnDelete (zero or one element)
  • Annotation elements (zero or more elements)

Applicable Attributes

The following table describes the attributes that can be applied to the End element when it is the child of an Association element.

Attribute Name Is Required Value
Type Yes The fully qualified name of the SSDL entity set that is at the end of the foreign key constraint.
Role No The value of the Role attribute in either the Principal or Dependent element of the corresponding ReferentialConstraint element (if used).
Multiplicity Yes 1, 0..1, or * depending on the number of rows that can be at the end of the foreign key constraint.
1 indicates that exactly one row exists at the foreign key constraint end.
0..1 indicates that zero or one row exists at the foreign key constraint end.
* indicates that zero, one, or more rows exist at the foreign key constraint end.

Note

Any number of annotation attributes (custom XML attributes) may be applied to the End element. However, custom attributes may not belong to any XML namespace that is reserved for CSDL. The fully-qualified names for any two custom attributes cannot be the same.

Example

The following example shows an Association element that defines the FK_CustomerOrders foreign key constraint. The Multiplicity values specified on each End element indicate that many rows in the Orders table can be associated with a row in the Customers table, but only one row in the Customers table can be associated with a row in the Orders table. Additionally, the OnDelete element indicates that all rows in the Orders table that reference a particular row in the Customers table will be deleted if the row in the Customers table is deleted.

 <Association Name="FK_CustomerOrders">
   <End Role="Customers"
        Type="ExampleModel.Store.Customers" Multiplicity="1">
     <OnDelete Action="Cascade" />
   </End>
   <End Role="Orders"
        Type="ExampleModel.Store.Orders" Multiplicity="*" />
   <ReferentialConstraint>
     <Principal Role="Customers">
       <PropertyRef Name="CustomerId" />
     </Principal>
     <Dependent Role="Orders">
       <PropertyRef Name="CustomerId" />
     </Dependent>
   </ReferentialConstraint>
 </Association>

End Element as a Child of the AssociationSet Element

The End element (as a child of the AssociationSet element) specifies a table at one end of a foreign key constraint in the underlying database.

An End element can have the following child elements (in the order listed):

  • Documentation (zero or one)
  • Annotation elements (zero or more)

Applicable Attributes

The following table describes the attributes that can be applied to the End element when it is the child of an AssociationSet element.

Attribute Name Is Required Value
EntitySet Yes The name of the SSDL entity set that is at the end of the foreign key constraint.
Role No The value of one of the Role attributes specified on one End element of the corresponding Association element.

Note

Any number of annotation attributes (custom XML attributes) may be applied to the End element. However, custom attributes may not belong to any XML namespace that is reserved for CSDL. The fully-qualified names for any two custom attributes cannot be the same.

Example

The following example shows an EntityContainer element with an AssociationSet element with two End elements:

 <EntityContainer Name="ExampleModelStoreContainer">
   <EntitySet Name="Customers"
              EntityType="ExampleModel.Store.Customers"
              Schema="dbo" />
   <EntitySet Name="Orders"
              EntityType="ExampleModel.Store.Orders"
              Schema="dbo" />
   <AssociationSet Name="FK_CustomerOrders"
                   Association="ExampleModel.Store.FK_CustomerOrders">
     <End Role="Customers" EntitySet="Customers" />
     <End Role="Orders" EntitySet="Orders" />
   </AssociationSet>
 </EntityContainer>

EntityContainer Element (SSDL)

An EntityContainer element in store schema definition language (SSDL) describes the structure of the underlying data source in an Entity Framework application: SSDL entity sets (defined in EntitySet elements) represent tables in a database, SSDL entity types (defined in EntityType elements) represent rows in a table, and association sets (defined in AssociationSet elements) represent foreign key constraints in a database. A storage model entity container maps to a conceptual model entity container through the EntityContainerMapping element.

An EntityContainer element can have zero or one Documentation elements. If a Documentation element is present, it must precede all other child elements.

An EntityContainer element can have zero or more of the following child elements (in the order listed):

  • EntitySet
  • AssociationSet
  • Annotation elements

Applicable Attributes

The table below describes the attributes that can be applied to the EntityContainer element.

Attribute Name Is Required Value
Name Yes The name of the entity container. This name cannot contain periods (.).

Note

Any number of annotation attributes (custom XML attributes) may be applied to the EntityContainer element. However, custom attributes may not belong to any XML namespace that is reserved for SSDL. The fully-qualified names for any two custom attributes cannot be the same.

Example

The following example shows an EntityContainer element that defines two entity sets and one association set. Note that entity type and association type names are qualified by the conceptual model namespace name.

 <EntityContainer Name="ExampleModelStoreContainer">
   <EntitySet Name="Customers"
              EntityType="ExampleModel.Store.Customers"
              Schema="dbo" />
   <EntitySet Name="Orders"
              EntityType="ExampleModel.Store.Orders"
              Schema="dbo" />
   <AssociationSet Name="FK_CustomerOrders"
                   Association="ExampleModel.Store.FK_CustomerOrders">
     <End Role="Customers" EntitySet="Customers" />
     <End Role="Orders" EntitySet="Orders" />
   </AssociationSet>
 </EntityContainer>

EntitySet Element (SSDL)

An EntitySet element in store schema definition language (SSDL) represents a table or view in the underlying database. An EntityType element in SSDL represents a row in the table or view. The EntityType attribute of an EntitySet element specifies the particular SSDL entity type that represents rows in an SSDL entity set. The mapping between a CSDL entity set and an SSDL entity set is specified in an EntitySetMapping element.

The EntitySet element can have the following child elements (in the order listed):

  • Documentation (zero or one element)
  • DefiningQuery (zero or one element)
  • Annotation elements

Applicable Attributes

The following table describes the attributes that can be applied to the EntitySet element.

Note

Some attributes (not listed here) may be qualified with the store alias. These attributes are used by the Update Model Wizard when updating a model.

Attribute Name Is Required Value
Name Yes The name of the entity set.
EntityType Yes The fully-qualified name of the entity type for which the entity set contains instances.
Schema No The database schema.
Table No The database table.

Note

Any number of annotation attributes (custom XML attributes) may be applied to the EntitySet element. However, custom attributes may not belong to any XML namespace that is reserved for SSDL. The fully-qualified names for any two custom attributes cannot be the same.

Example

The following example shows an EntityContainer element that has two EntitySet elements and one AssociationSet element:

 <EntityContainer Name="ExampleModelStoreContainer">
   <EntitySet Name="Customers"
              EntityType="ExampleModel.Store.Customers"
              Schema="dbo" />
   <EntitySet Name="Orders"
              EntityType="ExampleModel.Store.Orders"
              Schema="dbo" />
   <AssociationSet Name="FK_CustomerOrders"
                   Association="ExampleModel.Store.FK_CustomerOrders">
     <End Role="Customers" EntitySet="Customers" />
     <End Role="Orders" EntitySet="Orders" />
   </AssociationSet>
 </EntityContainer>

EntityType Element (SSDL)

An EntityType element in store schema definition language (SSDL) represents a row in a table or view of the underlying database. An EntitySet element in SSDL represents the table or view in which rows occur. The EntityType attribute of an EntitySet element specifies the particular SSDL entity type that represents rows in an SSDL entity set. The mapping between an SSDL entity type and a CSDL entity type is specified in an EntityTypeMapping element.

The EntityType element can have the following child elements (in the order listed):

  • Documentation (zero or one element)
  • Key (zero or one element)
  • Annotation elements

Applicable Attributes

The table below describes the attributes that can be applied to the EntityType element.

Attribute Name Is Required Value
Name Yes The name of the entity type. This value is usually the same as the name of the table in which the entity type represents a row. This value can contain no periods (.).

Note

Any number of annotation attributes (custom XML attributes) may be applied to the EntityType element. However, custom attributes may not belong to any XML namespace that is reserved for SSDL. The fully-qualified names for any two custom attributes cannot be the same.

Example

The following example shows an EntityType element with two properties:

 <EntityType Name="Customers">
   <Documentation>
     <Summary>Summary here.</Summary>
     <LongDescription>Long description here.</LongDescription>
   </Documentation>
   <Key>
     <PropertyRef Name="CustomerId" />
   </Key>
   <Property Name="CustomerId" Type="int" Nullable="false" />
   <Property Name="Name" Type="nvarchar(max)" Nullable="false" />
 </EntityType>

Function Element (SSDL)

The Function element in store schema definition language (SSDL) specifies a stored procedure that exists in the underlying database.

The Function element can have the following child elements (in the order listed):

  • Documentation (zero or one)
  • Parameter (zero or more)
  • CommandText (zero or one)
  • ReturnType (zero or more)
  • Annotation elements (zero or more)

A return type for a function must be specified with either the ReturnType element or the ReturnType attribute (see below), but not both.

Stored procedures that are specified in the storage model can be imported into the conceptual model of an application. For more information, see Querying with Stored Procedures. The Function element can also be used to define custom functions in the storage model.  

Applicable Attributes

The following table describes the attributes that can be applied to the Function element.

Note

Some attributes (not listed here) may be qualified with the store alias. These attributes are used by the Update Model Wizard when updating a model.

Attribute Name Is Required Value
Name Yes The name of the stored procedure.
ReturnType No The return type of the stored procedure.
Aggregate No True if the stored procedure returns an aggregate value; otherwise False.
BuiltIn No True if the function is a built-in1 function; otherwise False.
StoreFunctionName No The name of the stored procedure.
NiladicFunction No True if the function is a niladic2 function; False otherwise.
IsComposable No True if the function is a composable3 function; False otherwise.
ParameterTypeSemantics No The enumeration that defines the type semantics used to resolve function overloads. The enumeration is defined in the provider manifest per function definition. The default value is AllowImplicitConversion.
Schema No The name of the schema in which the stored procedure is defined.

1 A built-in function is a function that is defined in the database. For information about functions that are defined in the storage model, see CommandText Element (SSDL).

2 A niladic function is a function that accepts no parameters and, when called, does not require parentheses.

3 Two functions are composable if the output of one function can be the input for the other function.

Note

Any number of annotation attributes (custom XML attributes) may be applied to the Function element. However, custom attributes may not belong to any XML namespace that is reserved for SSDL. The fully-qualified names for any two custom attributes cannot be the same.

Example

The following example shows a Function element that corresponds to the UpdateOrderQuantity stored procedure. The stored procedure accepts two parameters and does not return a value.

 <Function Name="UpdateOrderQuantity"
           Aggregate="false"
           BuiltIn="false"
           NiladicFunction="false"
           IsComposable="false"
           ParameterTypeSemantics="AllowImplicitConversion"
           Schema="dbo">
   <Parameter Name="orderId" Type="int" Mode="In" />
   <Parameter Name="newQuantity" Type="int" Mode="In" />
 </Function>

Key Element (SSDL)

The Key element in store schema definition language (SSDL) represents the primary key of a table in the underlying database. Key is a child element of an EntityType element, which represents a row in a table. The primary key is defined in the Key element by referencing one or more Property elements that are defined on the EntityType element.

The Key element can have the following child elements (in the order listed):

  • PropertyRef (one or more)
  • Annotation elements

No attributes are applicable to the Key element.

Example

The following example shows an EntityType element with a key that references one property:

 <EntityType Name="Customers">
   <Documentation>
     <Summary>Summary here.</Summary>
     <LongDescription>Long description here.</LongDescription>
   </Documentation>
   <Key>
     <PropertyRef Name="CustomerId" />
   </Key>
   <Property Name="CustomerId" Type="int" Nullable="false" />
   <Property Name="Name" Type="nvarchar(max)" Nullable="false" />
 </EntityType>

OnDelete Element (SSDL)

The OnDelete element in store schema definition language (SSDL) reflects the database behavior when a row that participates in a foreign key constraint is deleted. If the action is set to Cascade, then rows that reference a row that is being deleted will also be deleted. If the action is set to None, then rows that reference a row that is being deleted are not also deleted. An OnDelete element is a child element of an End element.

An OnDelete element can have the following child elements (in the order listed):

  • Documentation (zero or one)
  • Annotation elements (zero or more)

Applicable Attributes

The following table describes the attributes that can be applied to the OnDelete element.

Attribute Name Is Required Value
Action Yes Cascade or None. (The value Restricted is valid but has the same behavior as None.)

Note

Any number of annotation attributes (custom XML attributes) may be applied to the OnDelete element. However, custom attributes may not belong to any XML namespace that is reserved for SSDL. The fully-qualified names for any two custom attributes cannot be the same.

Example

The following example shows an Association element that defines the FK_CustomerOrders foreign key constraint. The OnDelete element indicates that all rows in the Orders table that reference a particular row in the Customers table will be deleted if the row in the Customers table is deleted.

 <Association Name="FK_CustomerOrders">
   <End Role="Customers"
        Type="ExampleModel.Store.Customers" Multiplicity="1">
     <OnDelete Action="Cascade" />
   </End>
   <End Role="Orders"
        Type="ExampleModel.Store.Orders" Multiplicity="*" />
   <ReferentialConstraint>
     <Principal Role="Customers">
       <PropertyRef Name="CustomerId" />
     </Principal>
     <Dependent Role="Orders">
       <PropertyRef Name="CustomerId" />
     </Dependent>
   </ReferentialConstraint>
 </Association>

Parameter Element (SSDL)

The Parameter element in store schema definition language (SSDL) is a child of the Function element that specifies parameters for a stored procedure in the database.

The Parameter element can have the following child elements (in the order listed):

  • Documentation (zero or one)
  • Annotation elements (zero or more)

Applicable Attributes

The table below describes the attributes that can be applied to the Parameter element.

Attribute Name Is Required Value
Name Yes The name of the parameter.
Type Yes The parameter type.
Mode No In, Out, or InOut depending on whether the parameter is an input, output, or input/output parameter.
MaxLength No The maximum length of the parameter.
Precision No The precision of the parameter.
Scale No The scale of the parameter.
SRID No Spatial System Reference Identifier. Valid only for parameters of spatial types. For more information, see SRID and SRID (SQL Server).

Note

Any number of annotation attributes (custom XML attributes) may be applied to the Parameter element. However, custom attributes may not belong to any XML namespace that is reserved for SSDL. The fully-qualified names for any two custom attributes cannot be the same.

Example

The following example shows a Function element that has two Parameter elements that specify input parameters:

 <Function Name="UpdateOrderQuantity"
           Aggregate="false"
           BuiltIn="false"
           NiladicFunction="false"
           IsComposable="false"
           ParameterTypeSemantics="AllowImplicitConversion"
           Schema="dbo">
   <Parameter Name="orderId" Type="int" Mode="In" />
   <Parameter Name="newQuantity" Type="int" Mode="In" />
 </Function>

Principal Element (SSDL)

The Principal element in store schema definition language (SSDL) is a child element to the ReferentialConstraint element that defines the principal end of a foreign key constraint (also called a referential constraint). The Principal element specifies the primary key column (or columns) in a table that is referenced by another column (or columns). PropertyRef elements specify which columns are referenced. The Dependent element specifies columns that reference the primary key columns that are specified in the Principal element.

The Principal element can have the following child elements (in the order listed):

  • PropertyRef (one or more)
  • Annotation elements (zero or more)

Applicable Attributes

The following table describes the attributes that can be applied to the Principal element.

Attribute Name Is Required Value
Role Yes The same value as the Role attribute (if used) of the corresponding End element; otherwise, the name of the table that contains the referenced column.

Note

Any number of annotation attributes (custom XML attributes) may be applied to the Principal element. However, custom attributes may not belong to any XML namespace that is reserved for CSDL. The fully-qualified names for any two custom attributes cannot be the same.

Example

The following example shows an Association element that uses a ReferentialConstraint element to specify the columns that participate in the FK_CustomerOrders foreign key constraint. The Principal element specifies the CustomerId column of the Customer table as the principal end of the constraint.

 <Association Name="FK_CustomerOrders">
   <End Role="Customers"
        Type="ExampleModel.Store.Customers" Multiplicity="1">
     <OnDelete Action="Cascade" />
   </End>
   <End Role="Orders"
        Type="ExampleModel.Store.Orders" Multiplicity="*" />
   <ReferentialConstraint>
     <Principal Role="Customers">
       <PropertyRef Name="CustomerId" />
     </Principal>
     <Dependent Role="Orders">
       <PropertyRef Name="CustomerId" />
     </Dependent>
   </ReferentialConstraint>
 </Association>

Property Element (SSDL)

The Property element in store schema definition language (SSDL) represents a column in a table in the underlying database. Property elements are children of EntityType elements, which represent rows in a table. Each Property element defined on an EntityType element represents a column.

A Property element cannot have any child elements.

Applicable Attributes

The following table describes the attributes that can be applied to the Property element.

Attribute Name Is Required Value
Name Yes The name of the corresponding column.
Type Yes The type of the corresponding column.
Nullable No True (the default value) or False depending on whether the corresponding column can have a null value.
DefaultValue No The default value of the corresponding column.
MaxLength No The maximum length of the corresponding column.
FixedLength No True or False depending on whether the corresponding column value will be stored as a fixed length string.
Precision No The precision of the corresponding column.
Scale No The scale of the corresponding column.
Unicode No True or False depending on whether the corresponding column value will be stored as a Unicode string.
Collation No A string that specifies the collating sequence to be used in the data source.
SRID No Spatial System Reference Identifier. Valid only for properties of spatial types. For more information, see SRID and SRID (SQL Server).
StoreGeneratedPattern No None, Identity (if the corresponding column value is an identity that is generated in the database), or Computed (if the corresponding column value is computed in the database). Not Valid for RowType properties.

Note

Any number of annotation attributes (custom XML attributes) may be applied to the Property element. However, custom attributes may not belong to any XML namespace that is reserved for SSDL. The fully-qualified names for any two custom attributes cannot be the same.

Example

The following example shows an EntityType element with two child Property elements:

 <EntityType Name="Customers">
   <Documentation>
     <Summary>Summary here.</Summary>
     <LongDescription>Long description here.</LongDescription>
   </Documentation>
   <Key>
     <PropertyRef Name="CustomerId" />
   </Key>
   <Property Name="CustomerId" Type="int" Nullable="false" />
   <Property Name="Name" Type="nvarchar(max)" Nullable="false" />
 </EntityType>

PropertyRef Element (SSDL)

The PropertyRef element in store schema definition language (SSDL) references a property defined on an EntityType element to indicate that the property will perform one of the following roles:

  • Be part of the primary key of the table that the EntityType represents. One or more PropertyRef elements can be used to define a primary key. For more information, see Key element.
  • Be the dependent or principal end of a referential constraint. For more information, see ReferentialConstraint element.

The PropertyRef element can only have the following child elements:

  • Documentation (zero or one)
  • Annotation elements

Applicable Attributes

The table below describes the attributes that can be applied to the PropertyRef element.

Attribute Name Is Required Value
Name Yes The name of the referenced property.

Note

Any number of annotation attributes (custom XML attributes) may be applied to the PropertyRef element. However, custom attributes may not belong to any XML namespace that is reserved for CSDL. The fully-qualified names for any two custom attributes cannot be the same.

Example

The following example shows a PropertyRef element used to define a primary key by referencing a property that is defined on an EntityType element.

 <EntityType Name="Customers">
   <Documentation>
     <Summary>Summary here.</Summary>
     <LongDescription>Long description here.</LongDescription>
   </Documentation>
   <Key>
     <PropertyRef Name="CustomerId" />
   </Key>
   <Property Name="CustomerId" Type="int" Nullable="false" />
   <Property Name="Name" Type="nvarchar(max)" Nullable="false" />
 </EntityType>

ReferentialConstraint Element (SSDL)

The ReferentialConstraint element in store schema definition language (SSDL) represents a foreign key constraint (also called a referential integrity constraint) in the underlying database. The principal and dependent ends of the constraint are specified by the Principal and Dependent child elements, respectively. Columns that participate in the principal and dependent ends are referenced with PropertyRef elements.

The ReferentialConstraint element is an optional child element of the Association element. If a ReferentialConstraint element is not used to map the foreign key constraint that is specified in the Association element, an AssociationSetMapping element must be used to do this.

The ReferentialConstraint element can have the following child elements:

  • Documentation (zero or one)
  • Principal (exactly one)
  • Dependent (exactly one)
  • Annotation elements (zero or more)

Applicable Attributes

Any number of annotation attributes (custom XML attributes) may be applied to the ReferentialConstraint element. However, custom attributes may not belong to any XML namespace that is reserved for SSDL. The fully-qualified names for any two custom attributes cannot be the same.

Example

The following example shows an Association element that uses a ReferentialConstraint element to specify the columns that participate in the FK_CustomerOrders foreign key constraint:

 <Association Name="FK_CustomerOrders">
   <End Role="Customers"
        Type="ExampleModel.Store.Customers" Multiplicity="1">
     <OnDelete Action="Cascade" />
   </End>
   <End Role="Orders"
        Type="ExampleModel.Store.Orders" Multiplicity="*" />
   <ReferentialConstraint>
     <Principal Role="Customers">
       <PropertyRef Name="CustomerId" />
     </Principal>
     <Dependent Role="Orders">
       <PropertyRef Name="CustomerId" />
     </Dependent>
   </ReferentialConstraint>
 </Association>

ReturnType Element (SSDL)

The ReturnType element in store schema definition language (SSDL) specifies the return type for a function that is defined in a Function element. A function return type can also be specified with a ReturnType attribute.

The return type of a function is specified with the Type attribute or the ReturnType element.

The ReturnType element can have the following child elements:

  • CollectionType (one)

Note

Any number of annotation attributes (custom XML attributes) may be applied to the ReturnType element. However, custom attributes may not belong to any XML namespace that is reserved for SSDL. The fully-qualified names for any two custom attributes cannot be the same.

Example

The following example uses a Function that returns a collection of rows.

   <Function Name="GetProducts" IsComposable="true" Schema="dbo">
     <ReturnType>
       <CollectionType>
         <RowType>
           <Property Name="ProductID" Type="int" Nullable="false" />
           <Property Name="CategoryID" Type="bigint" Nullable="false" />
           <Property Name="ProductName" Type="nvarchar" MaxLength="40" Nullable="false" />
           <Property Name="UnitPrice" Type="money" />
           <Property Name="Discontinued" Type="bit" />
         </RowType>
       </CollectionType>
     </ReturnType>
   </Function>

RowType Element (SSDL)

A RowType element in store schema definition language (SSDL) defines an unnamed structure as a return type for a function defined in the store.

A RowType element is the child element of CollectionType element:

A RowType element can have the following child elements:

  • Property (one or more)

Example

The following example shows a store function that uses a CollectionType element to specify that the function returns a collection of rows (as specified in the RowType element).

   <Function Name="GetProducts" IsComposable="true" Schema="dbo">
     <ReturnType>
       <CollectionType>
         <RowType>
           <Property Name="ProductID" Type="int" Nullable="false" />
           <Property Name="CategoryID" Type="bigint" Nullable="false" />
           <Property Name="ProductName" Type="nvarchar" MaxLength="40" Nullable="false" />
           <Property Name="UnitPrice" Type="money" />
           <Property Name="Discontinued" Type="bit" />
         </RowType>
       </CollectionType>
     </ReturnType>
   </Function>

Schema Element (SSDL)

The Schema element in store schema definition language (SSDL) is the root element of a storage model definition. It contains definitions for the objects, functions, and containers that make up a storage model.

The Schema element may contain zero or more of the following child elements:

  • Association
  • EntityType
  • EntityContainer
  • Function

The Schema element uses the Namespace attribute to define the namespace for the entity type and association objects in a storage model. Within a namespace, no two objects can have the same name.

A storage model namespace is different from the XML namespace of the Schema element. A storage model namespace (as defined by the Namespace attribute) is a logical container for entity types and association types. The XML namespace (indicated by the xmlns attribute) of a Schema element is the default namespace for child elements and attributes of the Schema element. XML namespaces of the form https://schemas.microsoft.com/ado/YYYY/MM/edm/ssdl (where YYYY and MM represent a year and month respectively) are reserved for SSDL. Custom elements and attributes cannot be in namespaces that have this form.

Applicable Attributes

The table below describes the attributes can be applied to the Schema element.

Attribute Name Is Required Value
Namespace Yes The namespace of the storage model. The value of the Namespace attribute is used to form the fully qualified name of a type. For example, if an EntityType named Customer is in the ExampleModel.Store namespace, then the fully qualified name of the EntityType is ExampleModel.Store.Customer.
The following strings cannot be used as the value for the Namespace attribute: System, Transient, or Edm. The value for the Namespace attribute cannot be the same as the value for the Namespace attribute in the CSDL Schema element.
Alias No An identifier used in place of the namespace name. For example, if an EntityType named Customer is in the ExampleModel.Store namespace and the value of the Alias attribute is StorageModel, then you can use StorageModel.Customer as the fully qualified name of the EntityType.
Provider Yes The data provider.
ProviderManifestToken Yes A token that indicates to the provider which provider manifest to return. No format for the token is defined. Values for the token are defined by the provider. For information about SQL Server provider manifest tokens, see SqlClient for Entity Framework.

Example

The following example shows a Schema element that contains an EntityContainer element, two EntityType elements, and one Association element.

 <Schema Namespace="ExampleModel.Store"
       Alias="Self" Provider="System.Data.SqlClient"
       ProviderManifestToken="2008"
       xmlns="https://schemas.microsoft.com/ado/2009/11/edm/ssdl">
   <EntityContainer Name="ExampleModelStoreContainer">
     <EntitySet Name="Customers"
                EntityType="ExampleModel.Store.Customers"
                Schema="dbo" />
     <EntitySet Name="Orders"
                EntityType="ExampleModel.Store.Orders"
                Schema="dbo" />
     <AssociationSet Name="FK_CustomerOrders"
                     Association="ExampleModel.Store.FK_CustomerOrders">
       <End Role="Customers" EntitySet="Customers" />
       <End Role="Orders" EntitySet="Orders" />
     </AssociationSet>
   </EntityContainer>
   <EntityType Name="Customers">
     <Documentation>
       <Summary>Summary here.</Summary>
       <LongDescription>Long description here.</LongDescription>
     </Documentation>
     <Key>
       <PropertyRef Name="CustomerId" />
     </Key>
     <Property Name="CustomerId" Type="int" Nullable="false" />
     <Property Name="Name" Type="nvarchar(max)" Nullable="false" />
   </EntityType>
   <EntityType Name="Orders" xmlns:c="http://CustomNamespace">
     <Key>
       <PropertyRef Name="OrderId" />
     </Key>
     <Property Name="OrderId" Type="int" Nullable="false"
               c:CustomAttribute="someValue"/>
     <Property Name="ProductId" Type="int" Nullable="false" />
     <Property Name="Quantity" Type="int" Nullable="false" />
     <Property Name="CustomerId" Type="int" Nullable="false" />
     <c:CustomElement>
       Custom data here.
     </c:CustomElement>
   </EntityType>
   <Association Name="FK_CustomerOrders">
     <End Role="Customers"
          Type="ExampleModel.Store.Customers" Multiplicity="1">
       <OnDelete Action="Cascade" />
     </End>
     <End Role="Orders"
          Type="ExampleModel.Store.Orders" Multiplicity="*" />
     <ReferentialConstraint>
       <Principal Role="Customers">
         <PropertyRef Name="CustomerId" />
       </Principal>
       <Dependent Role="Orders">
         <PropertyRef Name="CustomerId" />
       </Dependent>
     </ReferentialConstraint>
   </Association>
   <Function Name="UpdateOrderQuantity"
             Aggregate="false"
             BuiltIn="false"
             NiladicFunction="false"
             IsComposable="false"
             ParameterTypeSemantics="AllowImplicitConversion"
             Schema="dbo">
     <Parameter Name="orderId" Type="int" Mode="In" />
     <Parameter Name="newQuantity" Type="int" Mode="In" />
   </Function>
   <Function Name="UpdateProductInOrder" IsComposable="false">
     <CommandText>
       UPDATE Orders
       SET ProductId = @productId
       WHERE OrderId = @orderId;
     </CommandText>
     <Parameter Name="productId"
                Mode="In"
                Type="int"/>
     <Parameter Name="orderId"
                Mode="In"
                Type="int"/>
   </Function>
 </Schema>

Annotation Attributes

Annotation attributes in store schema definition language (SSDL) are custom XML attributes in the storage model that provide extra metadata about the elements in the storage model. In addition to having valid XML structure, the following constraints apply to annotation attributes:

  • Annotation attributes must not be in any XML namespace that is reserved for SSDL.
  • The fully-qualified names of any two annotation attributes must not be the same.

More than one annotation attribute may be applied to a given SSDL element. Metadata contained in annotation elements can be accessed at runtime by using classes in the System.Data.Metadata.Edm namespace.

Example

The following example shows an EntityType element that has an annotation attribute applied to the OrderId property. The example also show an annotation element added to the EntityType element.

 <EntityType Name="Orders" xmlns:c="http://CustomNamespace">
   <Key>
     <PropertyRef Name="OrderId" />
   </Key>
   <Property Name="OrderId" Type="int" Nullable="false"
             c:CustomAttribute="someValue"/>
   <Property Name="ProductId" Type="int" Nullable="false" />
   <Property Name="Quantity" Type="int" Nullable="false" />
   <Property Name="CustomerId" Type="int" Nullable="false" />
   <c:CustomElement>
     Custom data here.
   </c:CustomElement>
 </EntityType>

Annotation Elements (SSDL)

Annotation elements in store schema definition language (SSDL) are custom XML elements in the storage model that provide extra metadata about the storage model. In addition to having valid XML structure, the following constraints apply to annotation elements:

  • Annotation elements must not be in any XML namespace that is reserved for SSDL.
  • The fully-qualified names of any two annotation elements must not be the same.
  • Annotation elements must appear after all other child elements of a given SSDL element.

More than one annotation element may be a child of a given SSDL element. Starting with the .NET Framework version 4, metadata contained in annotation elements can be accessed at runtime by using classes in the System.Data.Metadata.Edm namespace.

Example

The following example shows an EntityType element that has an annotation element (CustomElement). The example also shows an annotation attribute applied to the OrderId property.

 <EntityType Name="Orders" xmlns:c="http://CustomNamespace">
   <Key>
     <PropertyRef Name="OrderId" />
   </Key>
   <Property Name="OrderId" Type="int" Nullable="false"
             c:CustomAttribute="someValue"/>
   <Property Name="ProductId" Type="int" Nullable="false" />
   <Property Name="Quantity" Type="int" Nullable="false" />
   <Property Name="CustomerId" Type="int" Nullable="false" />
   <c:CustomElement>
     Custom data here.
   </c:CustomElement>
 </EntityType>

Facets (SSDL)

Facets in store schema definition language (SSDL) represent constraints on column types that are specified in Property elements. Facets are implemented as XML attributes on Property elements.

The following table describes the facets that are supported in SSDL:

Facet Description
Collation Specifies the collating sequence (or sorting sequence) to be used when performing comparison and ordering operations on values of the property.
FixedLength Specifies whether the length of the column value can vary.
MaxLength Specifies the maximum length of the column value.
Precision For properties of type Decimal, specifies the number of digits a property value can have. For properties of type Time, DateTime, and DateTimeOffset, specifies the number of digits for the fractional part of seconds of the column value.
Scale Specifies the number of digits to the right of the decimal point for the column value.
Unicode Indicates whether the column value is stored as Unicode.