Download - Entity Framework 1.3

8/10/2019 Entity Framework 1.3

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1 Copyright 2013 Infogain Corporation. All rights reserved.

November 15, 2014Copyright 2013 Infogain Corporation. All rights reserved.

Entity FrameworkAshok Sharma


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November 15, 2014

Copyright 2010 Infogain Corporation. All rights reserved.3

Why ORM


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Dr. EF. Codd


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DELETESELECT

COUNT

LEFTUNION MIN/MAX

JOIN

HAVINGORDER BY

RIGHT

INSERT

WHERE

UPDATE

Then we code in SQL


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SqlCommand oCmd;

SqlDataReader oDR;

string connString = ConfigurationManager.

ConnectionStrings["OracleConnString"].

ConnectionString;

SqlConnection conn = new SqlConnection(connString);

string selectQuery;

int _returnValue = 0;

selectQuery = SELECT COUNT(OrderID) from Orders where

EmployeeID=@EmpID;

conn.Open();

oCmd = new SqlCommand(selectQuery, conn);

oCmd.Parameters.Add(@EmpID, SqlDbType.Int);

oCmd.Parameters*@EmpID+.Value = employeeID;

oDR = oCmd.ExecuteReader();

if (oDR.Read())

_returnValue = oDR.GetInt32(0);

oDR.Close();

conn.Close();

ADO.NET code


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Developers like to work

with

Conceptual Models

Business Objects

Databases are designed for

Maintainability Security

Efficiency

Scalability


7/298 Copyright 2013 Infogain Corporation. All rights reserved.

using (SQLConnection conn = new SQLConnection();

{

conn.Open();

SQLCommand cmd = conn.CreateCommand();

cmd.CommandText = sp_StoredProc;

cmd.parameters.AddWithValue(@City, Dallas);

using (SQLDataReader rdr = cmd.ExecuteReader()){

while (rdr.read())

{

string name = rdr.GetString(0);

string city = rdr.GetString(1);

}}

}

Powerful, but fragile and time-consuming

8

Strings! No compile

time check or Intellisense

Parameters loosely bound: --

Names, types, number of

not checked until runtimeResults are loosely typed



ADO.NETADO

(1996)

DAO

(1992)

RDO

Application Connectivity Growth



The Impedance Mismatch

Relational

DatabaseConceptual /

Business Model

(Objects)



Enough! We need ORM!



What is it?

anAbstraction

technique for working with relational tables as if they were objects inmemory

Intention is to hide away the complexity of the underlying tables and give a

uniform way of working with dataWhy use it?

Developerproductivity

Retain database independence

Note:

Using an ORM does not mean you must use the ORM!



LinqToSQL Entity Framework


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November 15, 2014Copyright 2010 Infogain Corporation. All rights reserved.14

Entity Framework



Data access framework

Supports data-centric applications and services

Enables programming against a conceptual application model

Enables independency of any data storage engine or relational schema


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Items described in the EDM are called entities

Entities have only properties but no behavior

Entities can have relationships with other entities


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The model doesn't have any knowledge of the data storage

The backend data storage has no impact on your model or your code

Uses a provider model to interact with the data storage

Available providers:

SQL Server

Oracle

MySQL

Many more


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Automatically generates classes from the model

Takes care of all of the database connectivity

Provides common query syntax for querying the model

Provides a mechanism for tracking changes to the model's objects


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As metadata in XML

3 files

.CSDL (Conceptual Schema Definition Language)

conceptual abstraction which is exposed to the application.

SSDL (Store Schema Definition Language)

The mapping with your RDBMS data structure.

MSL (Mapping Schema Language) connects the CSDL and SSDL.


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The Three Parts of the Model:

The image is taken from Julia Lermans book Programming Entity Framework, 1st Edition


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EF automatically creates a set of classes from the model

You work with the model through the generated classes

Every change to the model can change the generated classes


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Queries are built against a data model

EDM query transform into data storage query Query results materialize into model entities

The image is

taken from

Julia Lermans

bookProgramming

Entity

Framework,

1st Edition


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1. Database to-Model : The first approach, which has existed since the initial

release of EF, is the ability to generate your model from a database.

2. Model-to-Database: generally knows as model-first, it lets developers start with a

conceptual model and generate their database based on that conceptual model.

3. Code Only Approach : It provides developers the ability to use the EntityFramework using POCO(Plain Old Class Object) entities and without an EDMX file.


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Download - Entity Framework 1.3

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