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Code Generation in LINQ to SQL
03/30/2017
.net-framework
dotnet-ado
article
ddcbdaa1-e7fa-4d85-a379-313b49965c07
4
JennieHubbard
jhubbard
jhubbard

Code Generation in LINQ to SQL

You can generate code to represent a database by using either the [!INCLUDEvs_ordesigner_long] or the SQLMetal command-line tool. In either case, end-to-end code generation occurs in three stages:

  1. The DBML Extractor extracts schema information from the database and reassembles the information into an XML-formatted DBML file.

  2. The DBML file is scanned by the DBML Validator for errors.

  3. If no validation errors appear, the file is passed to the Code Generator.

For more information, see SqlMetal.exe (Code Generation Tool). Developers using [!INCLUDEvs_current_short] can also use the [!INCLUDEvs_ordesigner_long] to generate code. See LINQ to SQL Tools in Visual Studio.

DBML Extractor

The DBML Extractor is a [!INCLUDEvbtecdlinq] component that takes database metadata as input and produces a DBML file as output.

Code Generator

The Code Generator is a [!INCLUDEvbtecdlinq] component that translates DBML files to [!INCLUDEvbprvb], C#, or XML mapping files.

XML Schema Definition File

The DBML file must be valid against the following schema definition as an XSD file.

Distinguish this schema definition file from the schema definition file that is used to validate an external mapping file. For more information, see External Mapping).

[!NOTE] [!INCLUDEvs_current_short] users will also find this XSD file in the XML Schemas dialog box as "DbmlSchema.xsd". To use the XSD file correctly for validating a DBML file, see How to: Validate DBML and External Mapping Files.

?<?xml version="1.0" encoding="utf-16"?>  
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="http://schemas.microsoft.com/linqtosql/dbml/2007" xmlns="http://schemas.microsoft.com/linqtosql/dbml/2007"  
elementFormDefault="qualified" >  
  <xs:element name="Database" type="Database" />  
  <xs:complexType name="Database">  
    <xs:sequence>  
      <xs:element name="Connection" type="Connection" minOccurs="0" maxOccurs="1" />  
      <xs:element name="Table" type="Table" minOccurs="0" maxOccurs="unbounded" />  
      <xs:element name="Function" type="Function" minOccurs="0" maxOccurs="unbounded" />  
    </xs:sequence>  
    <xs:attribute name="Name" type="xs:string" use="optional" />  
    <xs:attribute name="EntityNamespace" type="xs:string" use="optional" />  
    <xs:attribute name="ContextNamespace" type="xs:string" use="optional" />  
    <xs:attribute name="Class" type="xs:string" use="optional" />  
    <xs:attribute name="AccessModifier" type="AccessModifier" use="optional" />  
    <xs:attribute name="Modifier" type="ClassModifier" use="optional" />  
    <xs:attribute name="BaseType" type="xs:string" use="optional" />  
    <xs:attribute name="Provider" type="xs:string" use="optional" />  
    <xs:attribute name="ExternalMapping" type="xs:boolean" use="optional" />  
    <xs:attribute name="Serialization" type="SerializationMode" use="optional" />  
    <xs:attribute name="EntityBase" type="xs:string" use="optional" />  
  </xs:complexType>  
  <xs:complexType name="Table">  
    <xs:all>  
      <xs:element name="Type" type="Type" minOccurs="1" maxOccurs="1" />  
      <xs:element name="InsertFunction" type="TableFunction" minOccurs="0" maxOccurs="1" />  
      <xs:element name="UpdateFunction" type="TableFunction" minOccurs="0" maxOccurs="1" />  
      <xs:element name="DeleteFunction" type="TableFunction" minOccurs="0" maxOccurs="1" />  
    </xs:all>  
    <xs:attribute name="Name" type="xs:string" use="required" />  
    <xs:attribute name="Member" type="xs:string" use="optional" />  
    <xs:attribute name="AccessModifier" type="AccessModifier" use="optional" />  
    <xs:attribute name="Modifier" type="MemberModifier" use="optional" />  
  </xs:complexType>  
  <xs:complexType name="Type">  
    <xs:sequence>  
      <xs:choice minOccurs="0" maxOccurs="unbounded">  
        <xs:element name="Column" type="Column" minOccurs="0" maxOccurs="unbounded" />  
        <xs:element name="Association" type="Association" minOccurs="0" maxOccurs="unbounded" />  
      </xs:choice>  
      <xs:element name="Type" type="Type" minOccurs="0" maxOccurs="unbounded" />  
    </xs:sequence>  
    <xs:attribute name="IdRef" type="xs:IDREF" use="optional" />  
    <xs:attribute name="Id" type="xs:ID" use="optional" />  
    <xs:attribute name="Name" type="xs:string" use="optional" />  
    <xs:attribute name="InheritanceCode" type="xs:string" use="optional" />  
    <xs:attribute name="IsInheritanceDefault" type="xs:boolean" use="optional" />  
    <xs:attribute name="AccessModifier" type="AccessModifier" use="optional" />  
    <xs:attribute name="Modifier" type="ClassModifier" use="optional" />  
  </xs:complexType>  
  <xs:complexType name="Column">  
    <xs:attribute name="Name" type="xs:string" use="optional" />  
    <xs:attribute name="Member" type="xs:string" use="optional" />  
    <xs:attribute name="Storage" type="xs:string" use="optional" />  
    <xs:attribute name="AccessModifier" type="AccessModifier" use="optional" />  
    <xs:attribute name="Modifier" type="MemberModifier" use="optional" />  
    <xs:attribute name="Type" type="xs:string" use="required" />  
    <xs:attribute name="DbType" type="xs:string" use="optional" />  
    <xs:attribute name="IsReadOnly" type="xs:boolean" use="optional" />  
    <xs:attribute name="IsPrimaryKey" type="xs:boolean" use="optional" />  
    <xs:attribute name="IsDbGenerated" type="xs:boolean" use="optional" />  
    <xs:attribute name="CanBeNull" type="xs:boolean" use="optional" />  
    <xs:attribute name="UpdateCheck" type="UpdateCheck" use="optional" />  
    <xs:attribute name="IsDiscriminator" type="xs:boolean" use="optional" />  
    <xs:attribute name="Expression" type="xs:string" use="optional" />  
    <xs:attribute name="IsVersion" type="xs:boolean" use="optional" />  
    <xs:attribute name="IsDelayLoaded" type="xs:boolean" use="optional" />  
    <xs:attribute name="AutoSync" type="AutoSync" use="optional" />  
  </xs:complexType>  
  <xs:complexType name="Association">  
    <xs:attribute name="Name" type="xs:string" use="required" />  
    <xs:attribute name="Member" type="xs:string" use="required" />  
    <xs:attribute name="Storage" type="xs:string" use="optional" />  
    <xs:attribute name="AccessModifier" type="AccessModifier" use="optional" />  
    <xs:attribute name="Modifier" type="MemberModifier" use="optional" />  
    <xs:attribute name="Type" type="xs:string" use="required" />  
    <xs:attribute name="ThisKey" type="xs:string" use="optional" />  
    <xs:attribute name="OtherKey" type="xs:string" use="optional" />  
    <xs:attribute name="IsForeignKey" type="xs:boolean" use="optional" />  
    <xs:attribute name="Cardinality" type="Cardinality" use="optional" />  
    <xs:attribute name="DeleteRule" type="xs:string" use="optional" />  
    <xs:attribute name="DeleteOnNull" type="xs:boolean" use="optional" />  
  </xs:complexType>  
  <xs:complexType name="Function">  
    <xs:sequence>  
      <xs:element name="Parameter" type="Parameter" minOccurs="0" maxOccurs="unbounded" />  
      <xs:choice>  
        <xs:element name="ElementType" type="Type" minOccurs="0" maxOccurs="unbounded" />  
        <xs:element name="Return" type="Return" minOccurs="0" maxOccurs="1" />  
      </xs:choice>  
    </xs:sequence>  
    <xs:attribute name="Name" type="xs:string" use="required" />  
    <xs:attribute name="Id" type="xs:ID" use="optional" />  
    <xs:attribute name="Method" type="xs:string" use="optional" />  
    <xs:attribute name="AccessModifier" type="AccessModifier" use="optional" />  
    <xs:attribute name="Modifier" type="MemberModifier" use="optional" />  
    <xs:attribute name="HasMultipleResults" type="xs:boolean" use="optional" />  
    <xs:attribute name="IsComposable" type="xs:boolean" use="optional" />  
  </xs:complexType>  
  <xs:complexType name="TableFunction">  
    <xs:sequence>  
      <xs:element name="Argument" type="TableFunctionParameter" minOccurs="0" maxOccurs="unbounded" />  
      <xs:element name="Return" type="TableFunctionReturn" minOccurs="0" maxOccurs="1" />  
    </xs:sequence>  
    <xs:attribute name="FunctionId" type="xs:IDREF" use="required" />  
    <xs:attribute name="AccessModifier" type="AccessModifier" use="optional" />  
  </xs:complexType>  
  <xs:complexType name="Parameter">  
    <xs:attribute name="Name" type="xs:string" use="required" />  
    <xs:attribute name="Parameter" type="xs:string" use="optional" />  
    <xs:attribute name="Type" type="xs:string" use="required" />  
    <xs:attribute name="DbType" type="xs:string" use="optional" />  
    <xs:attribute name="Direction" type="ParameterDirection" use="optional" />  
  </xs:complexType>  
  <xs:complexType name="Return">  
    <xs:attribute name="Type" type="xs:string" use="required" />  
    <xs:attribute name="DbType" type="xs:string" use="optional" />  
  </xs:complexType>  
  <xs:complexType name="TableFunctionParameter">  
    <xs:attribute name="Parameter" type="xs:string" use="required" />  
    <xs:attribute name="Member" type="xs:string" use="required" />  
    <xs:attribute name="Version" type="Version" use="optional" />  
  </xs:complexType>  
  <xs:complexType name="TableFunctionReturn">  
    <xs:attribute name="Member" type="xs:string" use="required" />  
  </xs:complexType>  
  <xs:complexType name="Connection">  
    <xs:attribute name="Provider" type="xs:string" use="required" />  
    <xs:attribute name="Mode" type="ConnectionMode" use="optional" />  
    <xs:attribute name="ConnectionString" type="xs:string" use="optional" />  
    <xs:attribute name="SettingsObjectName" type="xs:string" use="optional" />  
    <xs:attribute name="SettingsPropertyName" type="xs:string" use="optional" />  
  </xs:complexType>  
  <xs:simpleType name="ConnectionMode">  
    <xs:restriction base="xs:string">  
      <xs:enumeration value="ConnectionString" />  
      <xs:enumeration value="AppSettings" />  
      <xs:enumeration value="WebSettings" />  
    </xs:restriction>  
  </xs:simpleType>  
  <xs:simpleType name="AccessModifier">  
    <xs:restriction base="xs:string">  
      <xs:enumeration value="Public" />  
      <xs:enumeration value="Internal" />  
      <xs:enumeration value="Protected" />  
      <xs:enumeration value="ProtectedInternal" />  
      <xs:enumeration value="Private" />  
    </xs:restriction>  
  </xs:simpleType>  
  <xs:simpleType name="UpdateCheck">  
    <xs:restriction base="xs:string">  
      <xs:enumeration value="Always" />  
      <xs:enumeration value="Never" />  
      <xs:enumeration value="WhenChanged" />  
    </xs:restriction>  
  </xs:simpleType>  
  <xs:simpleType name="SerializationMode">  
    <xs:restriction base="xs:string">  
      <xs:enumeration value="None" />  
      <xs:enumeration value="Unidirectional" />  
    </xs:restriction>  
  </xs:simpleType>  
  <xs:simpleType name="ParameterDirection">  
    <xs:restriction base="xs:string">  
      <xs:enumeration value="In" />  
      <xs:enumeration value="Out" />  
      <xs:enumeration value="InOut" />  
    </xs:restriction>  
  </xs:simpleType>  
  <xs:simpleType name="Version">  
    <xs:restriction base="xs:string">  
      <xs:enumeration value="Current" />  
      <xs:enumeration value="Original" />  
    </xs:restriction>  
  </xs:simpleType>  
  <xs:simpleType name="AutoSync">  
    <xs:restriction base="xs:string">  
      <xs:enumeration value="Never" />  
      <xs:enumeration value="OnInsert" />  
      <xs:enumeration value="OnUpdate" />  
      <xs:enumeration value="Always" />  
      <xs:enumeration value="Default" />  
    </xs:restriction>  
  </xs:simpleType>  
  <xs:simpleType name="ClassModifier">  
    <xs:restriction base="xs:string">  
      <xs:enumeration value="Sealed" />  
      <xs:enumeration value="Abstract" />  
    </xs:restriction>  
  </xs:simpleType>  
  <xs:simpleType name="MemberModifier">  
    <xs:restriction base="xs:string">  
      <xs:enumeration value="Virtual" />  
      <xs:enumeration value="Override" />  
      <xs:enumeration value="New" />  
      <xs:enumeration value="NewVirtual" />  
    </xs:restriction>  
  </xs:simpleType>  
  <xs:simpleType name="Cardinality">  
    <xs:restriction base="xs:string">  
      <xs:enumeration value="One" />  
      <xs:enumeration value="Many" />  
    </xs:restriction>  
  </xs:simpleType>  
</xs:schema>  

Sample DBML File

The following code is an excerpt from the DBML file created from the Northwind sample database. You can generate the whole file by using SQLMetal with the /xml option. For more information, see SqlMetal.exe (Code Generation Tool).

<?xml version="1.0" encoding="utf-16"?>  
<Database Name="northwnd" Class="Northwnd" xmlns="http://schemas.microsoft.com/dsltools/DLinqML">  
  
  <Table Name="Customers">  
    <Type Name="Customer">  
      <Column Name="CustomerID" Type="System.String" DbType="NChar(5) NOT NULL" IsPrimaryKey="True" CanBeNull="False" />  
      <Column Name="CompanyName" Type="System.String" DbType="NVarChar(40) NOT NULL" CanBeNull="False" />  
      <Column Name="ContactName" Type="System.String" DbType="NVarChar(30)" CanBeNull="True" />  
      <Column Name="ContactTitle" Type="System.String" DbType="NVarChar(30)" CanBeNull="True" />  
      <Column Name="Address" Type="System.String" DbType="NVarChar(60)" CanBeNull="True" />  
      <Column Name="City" Type="System.String" DbType="NVarChar(15)" CanBeNull="True" />  
      <Column Name="Region" Type="System.String" DbType="NVarChar(15)" CanBeNull="True" />  
      <Column Name="PostalCode" Type="System.String" DbType="NVarChar(10)" CanBeNull="True" />  
      <Column Name="Country" Type="System.String" DbType="NVarChar(15)" CanBeNull="True" />  
      <Column Name="Phone" Type="System.String" DbType="NVarChar(24)" CanBeNull="True" />  
      <Column Name="Fax" Type="System.String" DbType="NVarChar(24)" CanBeNull="True" />  
      <Association Name="FK_CustomerCustomerDemo_Customers" Member="CustomerCustomerDemos" ThisKey="CustomerID" OtherKey="CustomerID" OtherTable="CustomerCustomerDemo" DeleteRule="NO ACTION" />  
      <Association Name="FK_Orders_Customers" Member="Orders" ThisKey="CustomerID" OtherKey="CustomerID" OtherTable="Orders" DeleteRule="NO ACTION" />  
    </Type>  
  </Table>  
</Database>  

See Also

Background Information
External Mapping
How to: Generate the Object Model as an External File
Downloading Sample Databases
Reference