fix link warnings (#19831)

* fix duplicate headers

* work

* work

* update alt text

* update alt text

* update alt text

* clean up

* clean up

* clean up

* fix version links

* remove bogus space to get the report

Author: Rick-Anderson

aspnetcore/data/ef-rp/complex-data-model.md

@@ -55,7 +55,7 @@ The preceding code adds a `FullName` property and adds the following attributes
 
 For student enrollment dates, all of the pages currently display the time of day along with the date, although only the date is relevant. By using data annotation attributes, you can make one code change that will fix the display format in every page that shows the data. 
 
-The [DataType](/dotnet/api/system.componentmodel.dataannotations.datatypeattribute?view=netframework-4.7.1) attribute specifies a data type that's more specific than the database intrinsic type. In this case only the date should be displayed, not the date and time. The [DataType Enumeration](/dotnet/api/system.componentmodel.dataannotations.datatype?view=netframework-4.7.1) provides for many data types, such as Date, Time, PhoneNumber, Currency, EmailAddress, etc. The `DataType` attribute can also enable the app to automatically provide type-specific features. For example:
+The [DataType](/dotnet/api/system.componentmodel.dataannotations.datatypeattribute) attribute specifies a data type that's more specific than the database intrinsic type. In this case only the date should be displayed, not the date and time. The [DataType Enumeration](/dotnet/api/system.componentmodel.dataannotations.datatype) provides for many data types, such as Date, Time, PhoneNumber, Currency, EmailAddress, etc. The `DataType` attribute can also enable the app to automatically provide type-specific features. For example:
 
 * The `mailto:` link is automatically created for `DataType.EmailAddress`.
 * The date selector is provided for `DataType.Date` in most browsers.
@@ -85,11 +85,11 @@ For more information, see the [\<input> Tag Helper documentation](xref:mvc/views
 [StringLength(50, ErrorMessage = "First name cannot be longer than 50 characters.")]
 ```
 
-Data validation rules and validation error messages can be specified with attributes. The [StringLength](/dotnet/api/system.componentmodel.dataannotations.stringlengthattribute?view=netframework-4.7.1) attribute specifies the minimum and maximum length of characters that are allowed in a data field. The code shown limits names to no more than 50 characters. An example that sets the minimum string length is shown [later](#the-required-attribute).
+Data validation rules and validation error messages can be specified with attributes. The [StringLength](/dotnet/api/system.componentmodel.dataannotations.stringlengthattribute) attribute specifies the minimum and maximum length of characters that are allowed in a data field. The code shown limits names to no more than 50 characters. An example that sets the minimum string length is shown [later](#the-required-attribute).
 
 The `StringLength` attribute also provides client-side and server-side validation. The minimum value has no impact on the database schema.
 
-The `StringLength` attribute doesn't prevent a user from entering white space for a name. The [RegularExpression](/dotnet/api/system.componentmodel.dataannotations.regularexpressionattribute?view=netframework-4.7.1) attribute can be used to apply restrictions to the input. For example, the following code requires the first character to be upper case and the remaining characters to be alphabetical:
+The `StringLength` attribute doesn't prevent a user from entering white space for a name. The [RegularExpression](/dotnet/api/system.componentmodel.dataannotations.regularexpressionattribute) attribute can be used to apply restrictions to the input. For example, the following code requires the first character to be upper case and the remaining characters to be alphabetical:
 
 ```csharp
 [RegularExpression(@"^[A-Z]+[a-zA-Z]*$")]
@@ -745,7 +745,7 @@ Update *Models/Student.cs* with the following highlighted code:
 
 [!code-csharp[](intro/samples/cu21/Models/Student.cs?name=snippet_DataType&highlight=3,12-13)]
 
-The [DataType](/dotnet/api/system.componentmodel.dataannotations.datatypeattribute?view=netframework-4.7.1) attribute specifies a data type that's more specific than the database intrinsic type. In this case only the date should be displayed, not the date and time. The [DataType Enumeration](/dotnet/api/system.componentmodel.dataannotations.datatype?view=netframework-4.7.1) provides for many data types, such as Date, Time, PhoneNumber, Currency, EmailAddress, etc. The `DataType` attribute can also enable the app to automatically provide type-specific features. For example:
+The [DataType](/dotnet/api/system.componentmodel.dataannotations.datatypeattribute) attribute specifies a data type that's more specific than the database intrinsic type. In this case only the date should be displayed, not the date and time. The [DataType Enumeration](/dotnet/api/system.componentmodel.dataannotations.datatype) provides for many data types, such as Date, Time, PhoneNumber, Currency, EmailAddress, etc. The `DataType` attribute can also enable the app to automatically provide type-specific features. For example:
 
 * The `mailto:` link is automatically created for `DataType.EmailAddress`.
 * The date selector is provided for `DataType.Date` in most browsers.
@@ -775,14 +775,14 @@ Run the app. Navigate to the Students Index page. Times are no longer displayed.
 
 ### The StringLength attribute
 
-Data validation rules and validation error messages can be specified with attributes. The [StringLength](/dotnet/api/system.componentmodel.dataannotations.stringlengthattribute?view=netframework-4.7.1) attribute specifies the minimum and maximum length of characters that are allowed in a data field. The `StringLength` attribute
+Data validation rules and validation error messages can be specified with attributes. The [StringLength](/dotnet/api/system.componentmodel.dataannotations.stringlengthattribute) attribute specifies the minimum and maximum length of characters that are allowed in a data field. The `StringLength` attribute
 also provides client-side and server-side validation. The minimum value has no impact on the database schema.
 
 Update the `Student` model with the following code:
 
 [!code-csharp[](intro/samples/cu21/Models/Student.cs?name=snippet_StringLength&highlight=10,12)]
 
-The preceding code limits names to no more than 50 characters. The `StringLength` attribute doesn't prevent a user from entering white space for a name. The [RegularExpression](/dotnet/api/system.componentmodel.dataannotations.regularexpressionattribute?view=netframework-4.7.1) attribute is used to apply restrictions to the input. For example, the following code requires the first character to be upper case and the remaining characters to be alphabetical:
+The preceding code limits names to no more than 50 characters. The `StringLength` attribute doesn't prevent a user from entering white space for a name. The [RegularExpression](/dotnet/api/system.componentmodel.dataannotations.regularexpressionattribute) attribute is used to apply restrictions to the input. For example, the following code requires the first character to be upper case and the remaining characters to be alphabetical:
 
 ```csharp
 [RegularExpression(@"^[A-Z]+[a-zA-Z]*$")]

aspnetcore/data/ef-rp/concurrency.md

@@ -427,14 +427,14 @@ Optimistic concurrency includes the following options:
 
 When a property is configured as a [concurrency token](/ef/core/modeling/concurrency):
 
-* EF Core verifies that property has not been modified after it was fetched. The check occurs when [SaveChanges](/dotnet/api/microsoft.entityframeworkcore.dbcontext.savechanges?view=efcore-2.0#Microsoft_EntityFrameworkCore_DbContext_SaveChanges) or [SaveChangesAsync](/dotnet/api/microsoft.entityframeworkcore.dbcontext.savechangesasync?view=efcore-2.0#Microsoft_EntityFrameworkCore_DbContext_SaveChangesAsync_System_Threading_CancellationToken_) is called.
-* If the property has been changed after it was fetched, a [DbUpdateConcurrencyException](/dotnet/api/microsoft.entityframeworkcore.dbupdateconcurrencyexception?view=efcore-2.0) is thrown. 
+* EF Core verifies that property has not been modified after it was fetched. The check occurs when [SaveChanges](/dotnet/api/microsoft.entityframeworkcore.dbcontext.savechanges#Microsoft_EntityFrameworkCore_DbContext_SaveChanges) or [SaveChangesAsync](/dotnet/api/microsoft.entityframeworkcore.dbcontext.savechangesasync#Microsoft_EntityFrameworkCore_DbContext_SaveChangesAsync_System_Threading_CancellationToken_) is called.
+* If the property has been changed after it was fetched, a [DbUpdateConcurrencyException](/dotnet/api/microsoft.entityframeworkcore.dbupdateconcurrencyexception) is thrown. 
 
 The DB and data model must be configured to support throwing `DbUpdateConcurrencyException`.
 
 ### Detecting concurrency conflicts on a property
 
-Concurrency conflicts can be detected at the property level with the [ConcurrencyCheck](/dotnet/api/system.componentmodel.dataannotations.concurrencycheckattribute?view=netcore-2.0) attribute. The attribute can be applied to multiple properties on the model. For more information, see [Data Annotations-ConcurrencyCheck](/ef/core/modeling/concurrency#data-annotations).
+Concurrency conflicts can be detected at the property level with the [ConcurrencyCheck](/dotnet/api/system.componentmodel.dataannotations.concurrencycheckattribute) attribute. The attribute can be applied to multiple properties on the model. For more information, see [Data Annotations-ConcurrencyCheck](/ef/core/modeling/concurrency#data-annotations).
 
 The `[ConcurrencyCheck]` attribute isn't used in this tutorial.
 
@@ -545,7 +545,7 @@ Update *Pages\Departments\Edit.cshtml.cs* with the following code:
 
 [!code-csharp[](intro/samples/cu/Pages/Departments/Edit.cshtml.cs?name=snippet)]
 
-To detect a concurrency issue, the [OriginalValue](/dotnet/api/microsoft.entityframeworkcore.changetracking.propertyentry.originalvalue?view=efcore-2.0#Microsoft_EntityFrameworkCore_ChangeTracking_PropertyEntry_OriginalValue) is updated with the `rowVersion` value from the entity it was fetched. EF Core generates a SQL UPDATE command with a WHERE clause containing the original `RowVersion` value. If no rows are affected by the UPDATE command (no rows have the original `RowVersion` value), a `DbUpdateConcurrencyException` exception is thrown.
+To detect a concurrency issue, the [OriginalValue](/dotnet/api/microsoft.entityframeworkcore.changetracking.propertyentry.originalvalue#Microsoft_EntityFrameworkCore_ChangeTracking_PropertyEntry_OriginalValue) is updated with the `rowVersion` value from the entity it was fetched. EF Core generates a SQL UPDATE command with a WHERE clause containing the original `RowVersion` value. If no rows are affected by the UPDATE command (no rows have the original `RowVersion` value), a `DbUpdateConcurrencyException` exception is thrown.
 
 [!code-csharp[](intro/samples/cu/Pages/Departments/Edit.cshtml.cs?name=snippet_rv&highlight=24-999)]
 

aspnetcore/data/ef-rp/migrations.md

@@ -117,7 +117,7 @@ Run the app and verify that the database is seeded.
 
 ## Applying migrations in production
 
-We recommend that production apps **not** call [Database.Migrate](/dotnet/api/microsoft.entityframeworkcore.relationaldatabasefacadeextensions.migrate?view=efcore-2.0#Microsoft_EntityFrameworkCore_RelationalDatabaseFacadeExtensions_Migrate_Microsoft_EntityFrameworkCore_Infrastructure_DatabaseFacade_) at application startup. `Migrate` shouldn't be called from an app that is deployed to a server farm. If the app is scaled out to multiple server instances, it's hard to ensure database schema updates don't happen from multiple servers or conflict with read/write access.
+We recommend that production apps **not** call [Database.Migrate](/dotnet/api/microsoft.entityframeworkcore.relationaldatabasefacadeextensions.migrate#Microsoft_EntityFrameworkCore_RelationalDatabaseFacadeExtensions_Migrate_Microsoft_EntityFrameworkCore_Infrastructure_DatabaseFacade_) at application startup. `Migrate` shouldn't be called from an app that is deployed to a server farm. If the app is scaled out to multiple server instances, it's hard to ensure database schema updates don't happen from multiple servers or conflict with read/write access.
 
 Database migration should be done as part of deployment, and in a controlled way. Production database migration approaches include:
 
@@ -280,7 +280,7 @@ Run the app and verify that everything works.
 
 ## Applying migrations in production
 
-We recommend production apps should **not** call [Database.Migrate](/dotnet/api/microsoft.entityframeworkcore.relationaldatabasefacadeextensions.migrate?view=efcore-2.0#Microsoft_EntityFrameworkCore_RelationalDatabaseFacadeExtensions_Migrate_Microsoft_EntityFrameworkCore_Infrastructure_DatabaseFacade_) at application startup. `Migrate` shouldn't be called from an app in server farm. For example, if the app has been cloud deployed with scale-out (multiple instances of the app are running).
+We recommend production apps should **not** call [Database.Migrate](/dotnet/api/microsoft.entityframeworkcore.relationaldatabasefacadeextensions.migrate#Microsoft_EntityFrameworkCore_RelationalDatabaseFacadeExtensions_Migrate_Microsoft_EntityFrameworkCore_Infrastructure_DatabaseFacade_) at application startup. `Migrate` shouldn't be called from an app in server farm. For example, if the app has been cloud deployed with scale-out (multiple instances of the app are running).
 
 Database migration should be done as part of deployment, and in a controlled way. Production database migration approaches include:
 

aspnetcore/data/ef-rp/update-related-data.md

@@ -31,7 +31,7 @@ Create a *Pages/Courses/DepartmentNamePageModel.cs* file with the following code
 
 [!code-csharp[](intro/samples/cu30/Pages/Courses/DepartmentNamePageModel.cs)]
 
-The preceding code creates a [SelectList](/dotnet/api/microsoft.aspnetcore.mvc.rendering.selectlist?view=aspnetcore-2.0) to contain the list of department names. If `selectedDepartment` is specified, that department is selected in the `SelectList`.
+The preceding code creates a [SelectList](/dotnet/api/microsoft.aspnetcore.mvc.rendering.selectlist) to contain the list of department names. If `selectedDepartment` is specified, that department is selected in the `SelectList`.
 
 The Create and Edit page model classes will derive from `DepartmentNamePageModel`.
 
@@ -96,7 +96,7 @@ The page contains a hidden field (`<input type="hidden">`) for the course number
 
 ## Update the Course Details and Delete pages
 
-[AsNoTracking](/dotnet/api/microsoft.entityframeworkcore.entityframeworkqueryableextensions.asnotracking?view=efcore-2.0#Microsoft_EntityFrameworkCore_EntityFrameworkQueryableExtensions_AsNoTracking__1_System_Linq_IQueryable___0__) can improve performance when tracking isn't required.
+[AsNoTracking](/dotnet/api/microsoft.entityframeworkcore.entityframeworkqueryableextensions.asnotracking#Microsoft_EntityFrameworkCore_EntityFrameworkQueryableExtensions_AsNoTracking__1_System_Linq_IQueryable___0__) can improve performance when tracking isn't required.
 
 ### Update the Course page models
 
@@ -248,7 +248,7 @@ The Courses/Create and Courses/Edit pages each need a list of department names.
 
 [!code-csharp[](intro/samples/cu/Pages/Courses/DepartmentNamePageModel.cshtml.cs?highlight=9,11,20-21)]
 
-The preceding code creates a [SelectList](/dotnet/api/microsoft.aspnetcore.mvc.rendering.selectlist?view=aspnetcore-2.0) to contain the list of department names. If `selectedDepartment` is specified, that department is selected in the `SelectList`.
+The preceding code creates a [SelectList](/dotnet/api/microsoft.aspnetcore.mvc.rendering.selectlist) to contain the list of department names. If `selectedDepartment` is specified, that department is selected in the `SelectList`.
 
 The Create and Edit page model classes will derive from `DepartmentNamePageModel`.
 
@@ -313,7 +313,7 @@ Test the updated code. Create, edit, and delete a course.
 
 ## Add AsNoTracking to the Details and Delete page models
 
-[AsNoTracking](/dotnet/api/microsoft.entityframeworkcore.entityframeworkqueryableextensions.asnotracking?view=efcore-2.0#Microsoft_EntityFrameworkCore_EntityFrameworkQueryableExtensions_AsNoTracking__1_System_Linq_IQueryable___0__) can improve performance when tracking isn't required. Add `AsNoTracking` to the Delete and Details page model. The following code shows the updated Delete page model:
+[AsNoTracking](/dotnet/api/microsoft.entityframeworkcore.entityframeworkqueryableextensions.asnotracking#Microsoft_EntityFrameworkCore_EntityFrameworkQueryableExtensions_AsNoTracking__1_System_Linq_IQueryable___0__) can improve performance when tracking isn't required. Add `AsNoTracking` to the Delete and Details page model. The following code shows the updated Delete page model:
 
 [!code-csharp[](intro/samples/cu/Pages/Courses/Delete.cshtml.cs?name=snippet&highlight=21,23,40,41)]