The Entity Data Model

The Entity Data Model

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Objectives


Objectives
• Learn how to create and use an Entity Data
Model


Objectives
Model
• Explore the raw XML behind the model as a way
to understand how Entity Framework works


Objectives
Model
• Explore the raw XML behind the model as a way
to understand how Entity Framework works
• See how to use stored procedures within an
Entity Framework model


Agenda


Agenda
• Introduction


Agenda
• Introduction
• Creating and Using an Entity Data Model


Agenda
• Introduction
• Entity Data Model in the Raw


Agenda
• Introduction
• Entity Data Model in the Raw
• Using Stored Procedures in the Model


Introduction


Introduction
• Key link between entity objects and data


Introduction
 Conceptual model


Introduction
 Storage model


Introduction
 Storage model
 Mapping model


Introduction
 Storage model
 Mapping model
• Application design is often at odds with database
design


Introduction
 Storage model
 Mapping model
design
• Can work with model in designer


Introduction
 Storage model
 Mapping model
design
 Or get messy with the XML


Introduction
 Storage model
 Mapping model
design
• At build, split into three XML files


Introduction
 Storage model
 Mapping model
design
• At build, split into three XML files
• Developers don’t have to know the database

The Models within the Model


• Conceptual Model


 The actual Entity Data Model


 Provides what is needed to create data objects


• Storage Model


• Storage Model
 Represents the database schemas


• Storage Model
 Can be similar to conceptual model


• Storage Model
 Decupling of conceptual design from the database


• Storage Model
• Mapping Model


• Storage Model
• Mapping Model
 Bridge between conceptual and storage models


• Storage Model
• Mapping Model
 Bridge between conceptual and storage models
 Map object properties to database fields

Creating and Using an Entity Data
Model


Model
• Can create from scratch using XML


Model
 More productive using the designer


Model
• Three approaches


Model
 Database-first


Model
 Database-first
 Model-first


Model
 Database-first
 Model-first
 Code-first


Creating a Model Using Database-
First Design


First Design
• Directly supported by the Entity Framework
template


First Design
template
• Wizard lets you


First Design
template
• Wizard lets you
 Reverse-engineer the database schma


First Design
template
• Wizard lets you
 Select tables, views, and stored procedures to include


First Design
template
• Wizard lets you
 Select tables, views, and stored procedures to include
 Build the model from selected objects


Multiplicity


Multiplicity
• Used with associations


Multiplicity
• Number of entities that can be on each end of an
association


Multiplicity
association
 Sometimes referred to as cardinality


Multiplicity
association
• Three options


Multiplicity
association
• Three options
 One: 1


Multiplicity
association
• Three options
 One: 1
 Zero or one: 0..1


Multiplicity
association
• Three options
 One: 1
 Many: *


Multiplicity
association
• Three options
 One: 1
 Many: *
• Can combine in various ways, such as


Multiplicity
association
• Three options
 One: 1
 Many: *
 1:*


Multiplicity
association
• Three options
 One: 1
 Many: *
 1:*
 0..1:*


Multiplicity
association
• Three options
 One: 1
 Many: *
 1:*
 0..1:*
 *:*

Entity Data Model Object Properties


• Typical for Visual Studio


• Use Properties windows to set values of
properties for various objects


• Use Properties windows to set values of
properties for various objects
• Model stores some in model’s XML to define a
model, others guide object creation


Creating a Model Using
Model-First Design


Model-First Design
• Database-first design is common


Model-First Design
• Sometimes creating a new database with the
application


Model-First Design
application
 Could create the database first


Model-First Design
application
 But model-first is another option


Model-First Design
application
 Strictly speaking, Entity Framework has always had
this option


Model-First Design
application
this option
• Generate Database from Model option


Model-First Design
application
this option
• Generate Database from Model option
• Entity Designer Database Generation Power Pack


Sled Dog Event Registration


Sled Dog Event Registration
Team
Event
Race FirstName
Name 1 * 1 *
Distance LastName
EventDate
DogCount City
Sponsor
Trail Country
Location
DogCount

Mushing Skijoring
Leader1 Dog1
Leader2 Dog2
Dog3
NumberOfLeaders


Explore the Model with the
Model Browser


Model Browser
• Working with large models can be hard in the
designer


Model Browser
designer
 Can be hard to understand the structure of the model


Model Browser
designer
 Mapping Details windows doesn’t have details of
storage model


Model Browser
designer
 Mapping Details windows doesn’t have details of
storage model
• Overcome these limitations with the Model
Browser


Entity Data Model in the Raw


• Designer is a graphical view only of the conceptual
model


model
 Exposes most, but not all, features


model
 Ultimately, just a pretty face on the XML


model
• Need to have a basic understanding of the XML


model
 Sometimes have to manipulate the XML directly


model
• Can use any text editor


model
 But Visual Studio XML editor provides color-coding, well-
formedness checks, and Intellisense


model
 But Visual Studio XML editor provides color-coding, well-
formedness checks, and Intellisense
• Can’t have open in designer and XML simultaneously


XML Definition Languages


• One for each model:


 Conceptual model uses Conceptual Schema Definition
Language (CSDL)


Language (CSDL)
 Storage model uses Store Schema Definition
Language (SSDL)


Language (CSDL)
Language (SSDL)
 Mapping model uses Mapping Specification Language
(MSL)


Language (CSDL)
Language (SSDL)
 Mapping model uses Mapping Specification Language
(MSL)
• Visual Studio includes XML schema files


Model Build Mechanics


• .edmx file contains XML for all three models


 Plus support for the graphical designer


• Saves as three files at build:


 Conceptual model to .csdl file


 Storage model to .ssdl file


 Mapping model to .msl file


• By default, stored in project assembly


 Can output three physical files


 Can output three physical files
 Change the MetadataArtifactProcessing property of
the entity container

Using Stored Procedures in the
Model


Model
• Entity Framework can automatically generate all
code needed to do CRUD


Model
• Not necessarily ideal from DBA’s perspective


Model
 Job is to make sure data is secure, performs well, is
scalable, and meets needs of the application


Model
 Dynamic SQL complicates the job


Model
• Stored procedures vs. dynamic code


Model
 Pick one or the other and go for it


Model
• Entity Framework does both well


Model
• Entity Framework does both well
 Current version generates good code, mostly

Ways to Use Stored Procedures


• Few different ways


 Replace an entity’s insert, update, and delete
functions to use stored procedures


 Use stored procedures that return data to entities are
scalar values


 Use stored procedures that return data to entities are
scalar values
• Entity Framework uses terms stored procedure
and function interchangeably


Updating the Model from the
Database


Database
• Have to include stored procedures in the model
before you can use them


Database
 Only imported tables and views


Database
• Entity Framework supports updating the model from
the database


Database
the database
• Will use several stored procedures


Database
the database
 InsertCustomer, UpdateCustomer, and DeleteCustomer


Database
the database
 GetCustomersByRegion


Database
the database
 GetProductListByCategory


Database
the database
 GetProductListByCategory
 GetProductCategoryAveragePrice


Using Stored Procedures to
Change an Entity


Change an Entity
• One of the most common ways to use stored
procedures


Change an Entity
procedures
• Replaces Entity Framework default behavior for
an entity


Change an Entity
procedures
• Replaces Entity Framework default behavior for
an entity
• Will use the Customer object


Using Stored Procedures that
Read Data


Read Data
• Use stored procedures that read data in the model


Read Data
 Materialize an entity object


Read Data
 Random sets of data


Read Data
• GetCustomersByRegion returns all of the fields of
the Customer table


Read Data
the Customer table
• GetProductListByCategory returns fields from the
Product and ProductCategory tables


Read Data
the Customer table
• Complex type


Read Data
the Customer table
• Complex type
 Neither an entity or scalar type


Read Data
the Customer table
• Complex type
 Neither an entity or scalar type
 Use Model Browser to work with


Return a Scalar Value


• Another option is to retrieve a scalar value from
a stored procedure


a stored procedure
• Dirty little secret


a stored procedure
 Stored procedure still returns a result set


a stored procedure
 Stored procedure still returns a result set
 Entity Framework extracts the value, sort of


Learn More!


Learn More!
• This is an excerpt from a larger course. Visit
www.learnnowonline.com for the full details!


Learn More!

• Learn more about Entity Framework on
SlideShare:


Learn More!

• Learn more about Entity Framework on
SlideShare:
 Introducing the Entity Framework


The Entity Data Model

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