DataAccess using ADO.NET

8/9/2019 DataAccess using ADO.NET

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Data Access with

ADO.NET 3.5

Claeys Kurt

www.devitect.net

26/03/09


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LINQ as query language LINQ to SQL

LINQ to Entities (=ADO.NET Entity Framework)

ENTITY SQL

ADO.NET DataServices

ASP.NET Dynamic Data

ADO.NET 3.5


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Overview

LINQ Enabled Datasources

LINQ Enabled ADO.NET

Objects

XMLRelational

C# VB ....NET Language-Integrated Query (LINQ)

LINQ to

Objects

LINQ to

DataSet

LINQ to

SQL

LINQ to

Entities

LINQ to

XML


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LINQ as Query Language

from idin source

{ from idin source |

join idin source on exprequals expr[ into id] |

let id= expr|

where condition |

orderby ordering, ordering, }

select expr| group exprby key

[ into id query]

Starts withfrom

Zero or morefrom,join, let, where, ororderby

Ends withselector group by

Optional intocontinuation


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var contacts =from c in customers

where c.State == "WA"select new { c.Name, c.Phone };

var contacts =customers.Where(c => c.State == "WA").Select(c => new { c.Name, c.Phone });

Extension

methods

Lambda

expressions

Query

expressions

Object

initializers

Anonymous

types

Local variable

type inference

LINQ as Query Language


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Query Expressions

Project Select Filter Where , Distinct

Test Any(), All()

Join Join On Equals

Group Group By , Into ,

Group Join On Equals Into

Aggregate Count(), Sum(), Min(), Max(),Avg()

Partition Skip [ While ] , Take [ While ] Set Union, Intersect, Except

Order Order By , [ Ascending | Descending ]


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LINQ Architecture

System.Linq.EnumerableDelegate based

Source implements

IEnumerable

var query = from c in customers where c.City == "Hove" select c.Name;

var query = customers.Where(c => c.City == "Hove").Select(c => c.Name);

System.Linq.QueryableExpression tree based

Source implements

IQueryable

SQL DataSetsCollection of

objects inmemory

Others


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OR Mapping

Data Objects !


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Store

Application

Collection of Objects

OR Mapper

LINQ Query

T-SQL Query

SQL Tabular Data

Collection in memory

Tables

OR Mapping


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Level ofAbstraction

Low-level:databaseschema

Higher-level:

conceptualschema

QueryLanguage

Query inquotes

Language-

IntegratedQuery (LINQ)

QueryResults

Loosely-typed(brittle, error-

prone)

Strongly-typed

ADO.NET 2.0

ADO.NET 3.5

Data Access Evolution


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Demo on LINQ to SQL


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Entity Framework

Schema independence

Store independence

Higher level constructs Relationships

Inheritance

Composite Entities

Conceptual Model

.NET Provider

(EntitySQL)

ORM & LINQ

V3.0

Store

M

apping


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Entity Framework

.NET Entity Provider (Entity SQL)

Command

ConnectionReader

EF

Store.NET Data Provider

V2.0

Command

ConnectionReader

Adapter

EF

Conceptual Model

Entity Entity

relationship

Mapping (MSL)

EF Programming Model

Updating through the ObjectContext

Quering with LINQ or Entity SQL


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O/R Mapping

MappingConceptual MappingLogical

*

*


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3 Layers

The logical store model that represents the relational schema from a database.

Logical layer (SSDL)

The mapping between CSDL and SSDL.

Mapping layer(MSL)

The conceptual entity model that represents the entities and their associations and

inheritance structure.

Conceptual layer(CSDL)


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TPC MappingFowler : Concrete Table Inheritance

Microsoft : Table Per Concrete Type (TPC)Represents an inheritance hierarchy of classes with one

table per concrete class in the hierarchy


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TPT MappingFowler : Class Table Inheritance

Microsoft : Table Per Type (TPT)Represents an inheritance hierarchy of classes with one

table for each class


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TPH MappingFowler : Single Table Inheritance

Microsoft : Table Per Hierarchy (TPH)

Represents an inheritance hierarchy of classes as a single table

that has columns for all the fields of the various classes.


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The Role of the ObjectContext

ObjectContext

DatabaseTables

Attach

1. Query

Notifies

2. Update the Entities

ChangeTracking

3. Save Changes


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Demo on Entity Framework

i


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Project Astoria, ASP.NET extensions

Exposing data (CRUD)

Needs conceptual model (L2S or EF)

Lightweight HTTP based access (no soap)

Supports URI translation

Atom/JSON wire formats

IQueryable interface IUpdatable interface

System.Data.Services namespace

ADO.NET DataServices

RESTFul !

RESTF l ?


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Resources

Res 1

Res 2

Res 3

Res 4

HTTP Request

URL

VERB

Payload

HTTP Response

Status

GET

POST

PUTDELETEXML JSON

Payload

XML JSON

RESTFul ?


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Demo on ADO.NET DataServices

ASP NET D i D


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Create a webapp to maintain a database with

no coding !

UI based on templates

Needs conceptual model (L2S or EF)

HTTP based access


ASP NET D i D t


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Uses DynamicData Controls to build editable

screens.

Builds in Paging, Sorting, Filtering, and

Validation automatically.

Dynamic Data fields for rendering individual

data types.

Allows a great deal of customization.


ASP NET D i D t


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Demo on ASP.NET Dynamic Data

DataAccess using ADO.NET

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