ADO.NET

Objectives

Introduce Microsoft® ADO.NET

Show the evolution of ADO to ADO.NET

Introduce the primary components of ADO.NET

Contents

Differences Between ADO and ADO.NET

Benefits of ADO.NET

ADO.NET Core Concepts and Architecture The ADO.NET Object Model The DataSet and Data Views Managed Providers

ADO.NET and the .NET Framework

Microsoft .NET Framework

Common Language Runtime

Base Classes

Web Services User Interface

Data and XML

ADO.NET XML ... ...

ADO vs. ADO.NET 1/2

ADO Designed for connected access Tied to the physical data model The RecordSet is the central data container RecordSet is one (1) table that contains all the data

Retrieving data from > 1 table or source requires a database JOIN

Data is “flattened”: lose relationships; navigation is sequential

Data types are bound to COM/COM+ data types Data sharing via COM marshalling Problems marshalling through firewalls (DCOM, binary)

ADO vs. ADO.NET 2/2

ADO.NET Designed for disconnected access Can model data logically! The DataSet replaces the RecordSet DataSet can contain multiple tables

Retrieving data from > 1 table or source does not require a JOIN

Relationships are preserved: navigation is relational

Data types are only bound to XML schema No data type conversions required XML, like HTML, is plaintext: “Firewall friendly”

Benefits of ADO.NET Interoperability through use of XML (more later!)

Open standard for data that describes itself Human readable and decipherable text Used internally but accessible externally

Can use XML to read and write and move data

Scalability through the disconnected DataSet Connections are not maintained for long periods Database locking does not occur

Locking support with ServiceComponents

Optimistic locking otherwise

Works the way the Web works: “Hit and Run!”

Maintainability Separation of data logic and user interface

Visual Studio.NET Enhancements

Typed programming—a programming style Uses end-user words: Easier to read and write Statement completion in Microsoft Visual Studio.NET Safer: Provides compile-time checking Examples:

Untyped: Table("Customer")("Jones").Column(“Balance”) Typed: myDataSet.Customer("Jones").Balance

Wizard support Generates queries for you Graphical way to select data you want to work with XML Designer (for creating DataSets)

Core Concepts and Architecture

The ADO.NET Object Model Objects of System.Data .NET data providers

ADO.NET namespace hierarchy Organizes the object model Includes:

System.Data System.Data.OleDb System.Data.Common System.Data.SqlClient System.Data.SqlTypes

ADO.NET

ADO.NET-related Namespaces

System.Data

.OleDb.SqlClient.SqlTypes .Common

System.Data Namespace

Contains the basis and bulk of ADO.NET

Data-centric namespace

Provides the means to work on and with your data! Classes and methods to manipulate your data Ability to create views of your data Means to logically represent your data Enables the use of XML to view, share, and store data

Introducing the Objects…

Contains the “main” classes of ADO.NET

In-memory cache of data

In-memory cache of a database table

Used to manipulate a row in a DataTable

Used to define the columns in a DataTable

Used to relate 2 DataTables to each other

Used to create views on DataSets

System.Data

DataTable

DataRow

DataRelation

DataColumn

DataViewManager

DataSet

DataSet Tables

DataTable

Putting the Objects Together…

Relations

DataRelation

DataRelation

DataRow(s)

DataColumn

Constraint(s)

DataTable

DataTable

DataView

DataViewManager

Working Data - The DataSet

An in-memory cache of data from a data source

Common way to represent and manipulate data Universal data container Not just for use with databases

Logical or physical representation of data

Designed to be disconnected from the data source Connect, execute query, disconnect

Can use XML To read and write data To read and write XMLSchema

Properties & Methods of Interest

Collections are used to add & remove tables & relations

Properties of Interest: Tables: Returns the collection of DataTable objects Relations: Returns the collection of DataRelations Namespace: Gets or sets the namespace of the DataSet

Using Properties Samples: myDataSet.Tables.Add( myTable ); myDataTableCollection = myDataSet.Tables

All About Data!

Universal Data Container

DataSet: It’s not just for Databases

The DataTable May be mapped to a physical table in the data source

Can be related to one another through DataRelations

Optimistic concurrency or locking - model

Properties of Interest: Columns: Returns ColumnsCollection of DataColumns Rows: Returns DataRow objects as a RowsCollection ParentRelations: Returns the RelationsCollection Constraints: Returns the table’s ConstraintsCollection DataSet: Returns the DataSet of the DataTable PrimaryKey: Gets the DataColumns that make up the

table’s primary key

System.Data—DataSet and DataTable Create a DataTable and add it to a DataSet

DataSet ds = new DataSet();

// Create DataTable object: “Customers”.DataTable dt= new DataTable( “Customers” );

// Create and add columns to the table // 1. Explicitly create and Add a DataColumnDataColumn dc; dc = new DataColumn( “CustID”, Type.GetType("System.Int16"));dt.Columns.Add( dc );

// 2. Implicitly Create and Add columns (DataColumn).dt.Columns.Add( “First_Name”,Type.GetType("System String”));dt.Columns.Add( “Last_Name”, Type.GetType("System String”));

// Add the DataTable object to the DataSetds.Tables.Add( dt );

Relating Data - The DataRelation

Used to create logical relations between your data Create relations between two (2) DataTable objects Requires a DataColumn object from each DataTable The DataType of both DataColumns must be the same

Cannot relate a Int32 DataColumn and a String DataColumn

The relation is named (by you!) DataRelation dr=new DataRelation( “myRelation”,...)

Makes relational navigation possible

RelationsCollection used to hold/group them Accessed through the DataSet’s Relations property

Creating Relations With DataRelations

// Building on the DataTable example earlier... // Get the DataTable DataColumns we want to relate...DataColumn parentCol, childCol;parentCol= DataSet.Tables["Customers"].Columns["CustID"];childCol = DataSet.Tables["Orders“].Columns["CustID"];

// Create DataRelation with the name “CustomerOrders”... DataRelation dr = new DataRelation("CustomersOrders", parentCol, childCol);

// Add the relation to the DataSet... ds.Relations.Add( dr );

XML and the DataSet DataSet can read/write XML for its data and/or schema

You can create or modify data in a DataSet using XML You can create or modify the DataSets schema using XML

XML-related DataSet methods for reading: ReadXml: Reads an XML schema and data into the DataSet ReadXmlSchema: Reads an XML schema into the DataSet

And for writing: WriteXml, WriteXmlSchema GetXml, GetXmlSchema

Namespace property: sets the namespace for serialization

Full support for SQL Server-style DiffGrams

Methods of Reading and Writing XML // Code for creating the DataSet mds and loading the // DataSet from a data source not shown.

String oFile = “C:\\My_ADO.NET\\myXmlOutput.xsd”;String iFile = “C:\\My_ADO.NET\\myXmlInput.xsd”; // Write the DataSet’s XMLSchema to an XML Documentmds.WriteXmlSchema( oFile );

// Read/Upload XML Data into the DataSetmds.ReadXml( iFile);

// modify the data // ...

// Write the existing Data to an XML Documentmds.WriteXml( "C:\\My_ADO.NET\\myXmlData.txt", XmlWriteMode.DiffGram);

DataViewManager

DataViewSettings

DataSet Tables

DataTable

DataSet, DataRelation, Data…Views

Relations

DataRelation

DataRelation

DataRow(s)

DataColumn

Constraint(s)

DataTable

DataTable

DataView

DataViewSetting

DataViewSetting

Viewing Data - The DataView

Create multiple views on DataTable objects Bindable to user interface controls Properties of Interest:

Table: Retrieves or sets the associated DataTable Sort: Gets or sets the table’s sort columns and sort order RowFilter: Gets or sets the expression used to filter rows RowStateFilter: Gets or sets the row state filter

None, Unchanged, New, Deleted, ModifiedCurrent, and others

Creating a DataView by Example

// Code for myTable “Customers” with “Name” column not shownDataView view1 = new DataView( myTable );DataView view2 = new DataView( myTable );

// Creates Ascending view of Customers by “Name”view1.Sort = “Name ASC”;

// Set the view to show only modified (original) rows view2.RowStateFilter= DataViewRowState.ModifiedOriginal;

// Bind to UI element(s)... DataGrid myGrid = new DataGrid();myGrid.SetDataBinding( view1, “Customer”);

//...

Viewing More Data - DataViewManager

Similar to a DataView but DataSet oriented

Used to create multiple views on a DataSet Ability to automatically set filters on the tables

Properties of Interest: DataViewSettings: Gets the DataView for on each DataTable DataSet: Gets or sets the DataSet to be viewed

CreateDataView method Creates a DataView on a DataTable

DataViewManager By Example // Create the DataViewManager & views...DataViewManager dvMgr = new DataViewManager( myDS );dvMgr.CreateDataView( ds.Tables[“Orders"] );dvMgr.DataViewSettings[“Orders"].Sort = “CustID ASC";

dvMgr.CreateDataView( ds.Tables[“Customers"] );dvMgr.DataViewSettings[“Customers"].Sort = “Name DESC";

// Bind to a UI elements/controls...dataGrid1.DataSource = viewMgr;dataGrid1.DataMember = "Table1";

dataGrid2.DataSource = viewMgr;dataGrid2.DataMember = "Table2";

// Update the control with the data...dataGrid1.Update();dataGrid2.Update();

The (ADO).NET Data Providers

A collection of classes for accessing data sources: Microsoft SQL Server™ 2000, SQL Server 7, and MSDE Any OLE Database (OLE DB) providers

Including: Oracle, JET, and SQL OLE DB Providers

Establish connection between DataSets and data stores

Two .NET data providers: ADO: via the System.Data.OleDb namespace SQL Server: via the System.Data.SqlClient namespace

System.Data.OleDb is the .NET data provider

.NET Data Providers Hierarchy

System.Data

.OleDb.SqlClient

OleDbCommandOleDbConnectionOleDbDataReaderOleDbDataAdapter

SqlCommandSqlConnectionSqlDataReader

SqlDataAdapter

.Common Contains classes shared by both

OleDbConnection and SqlConnection

Represent a unique session with a data source

Create, open, close a connection to a data source

Functionality and methods to perform transactions

OleDbConnection example:

String conStr="Provider=Microsoft.Jet.OLEDB.4.0;" + "Data Source=NWIND_RW.MDB";OleDbConnection aConn = new OleDbConnection(conStr);aConn.Open(); // Execute Queries using OleDbDataAdapter ClassaConn.Close();

OleDbDataAdapter Class 1/2

Bridge between the DataSet and the data store Inherited from the DataAdapter class

Means to modify the DataSet and data source

data store DataSetDataAdapter

OleDbDataAdapter Class 2/2

Properties of Interest: DeleteCommand: The delete command expressed in SQL InsertCommand: Gets or sets insert command SelectCommand: Gets or sets select command UpdateCommand: Gets or sets update command TableMappings: Maps source table and a DataTable

OleDbCommands retrieved or set by command properties

Implements abstract methods of the DataAdapter class: public abstract int Fill( DataSet dataSet ); public abstract int Update( DataSet dataSet );

OleDbCommand Class

Represents a query to execute on the data source May be a SQL statement or stored procedure

Properties of Interest: Connection: Get or set the data source connection CommandText: Get or set the query (text) command

A SQL statement or the name of the stored procedure

CommandType: Get/set how the command is interpreted Text, StoredProcedure, or TableDirect

CommandTimeout: The seconds until connection timeout

OleDbDataReader 1/2

Forward-only data access

“Lightweight” programming model Less overhead than using OleDbDataAdapter

Instantiated & returned by OleDbCommand.ExecuteReader

Ties up the OleDbCommand until it is finished reading

OleDbDataReader 2/2

Properties of Interest: FieldCount: Returns the number of fields in the result set RecordsAffected: Number of affected records

Methods to retrieve data: By column type and/or index: GetValue; GetString; etc. Read(): Advances reader to next record NextResult(): Advanced to next result set in batch GetValues(): Gets the current row

OleDbDataReader Sample // Code for creating the OleDbConnection “adoConn” not shownString myQuery = “SELECT * FROM Customers”;adoConn.Open();OleDbCommand myCmd = new OleDbCommand( myQuery,adoConn );

// Declare the OleDbDataReader & // then instantiate it with ExecuteReader(...) ...OleDbDataReader reader = myCmd.ExecuteReader();

// Always call Read before accessing data. while( reader.Read() ) { Object [] cols = new Object[10] ; reader.GetValues( cols ); Console.WriteLine( cols[0].ToString() + " | " + cols[1] );} // Always Close the reader and the connection when donereader.Close();adoConn.Close();

Summary

ADO.NET is the evolution of ADO

It is a disconnected, Web-centric model

Flexible in its ability to work with data

Increases your ability to logically organize data

Extensive support for XML Facilitates working with and sharing data

Interacts with a wide variety of data sources

Questions ?

Duwamish Books

A Sample Application for Microsoft .NET

Installing the Sample 1/2

Install the "Enterprise Samples" with Visual Studio.NET

Location of the C# Version Visual Studio.NET folder Directory .\EnterpriseSamples\DuwamishOnline CS

Location of the Visual Basic® Version Directory .\EnterpriseSamples\DuwamishOnline VB

Installation Tasks Check the prerequsites

Microsoft Windows® 2000 Server, SQL Server 2000 with English Query optional and supported

Read the Readme.htm

Run Installer Duwamish.msi (double-click it)

Installing the Sample 2/2

The installation wizard will guide you

Defaults should be OK for almost everybody

Setup will install database, Web site, and code

After installation is complete: File/Open Solution with the Duwamish.sln file Can build the sample with Build/Build Solution

User / Browser

IIS

Duwamish Architecture Overview

DataAccess

Database

Com

mon.D

ata

BusinessRules

BusinessFacade

System

Fram

ework

Web

ASP.NET

ADO.NET

Common Components Duwamish7.Common

Contains systems configuration options Contains common data definitions (classes)

Namespace Duwamish.Common.Data

"Internal" data representation for Book, Category, Customer, OrderData

Duwamish7.SystemFramework Diagnostics utilities Pre and post condition checking classes Dynamic configuration In short:

Everything that's pure tech and not business code

Duwamish7.DataAccess

Contains all database-related code

Uses ADO.NET architecture Using SQL Server managed provider Shows DataSet, DataSetCommand usage

Optimized for performance by using stored procs

Duwamish7.BusinessRules

Implements all business rules Validation of business objects (for example,

Customer EMail) Updating business objects Calculations (Shipping Cost, Taxes)

All data access performed through DataAccess

Duwamish7.BusinessFacade

Implements logical business subsystems CustomerSystem: Profile management OrderSystem: Order management ProductSystem: Catalog

Reads data through DataAccess

Data validated and updated using BusinessRules

BusinessFacade encapsulates all business-related functionality

Duwamish7.Web

Implements the user interface for Web access

Uses ASP.NET architecture Employs Web Forms model Uses code behind forms Manages state Uses custom Web Controls

All functionality accessed through BusinessFacade

Shop at Duwamish Online.NET

Demo: Duwamish in Action

Exploring Duwamish ADO.NET

Exploring ADO.NET Features in Duwamish

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