Introduction to Database Processing

with ADO.NET

Slide 2

The ASP.NET / ADO.NET Conundrum The tools and wizards are wonderful for

simple applications As applications become more complex

and “real” You need to write code between the

controls and the data providers Nested controls and one-to-many views

become complex At some point, the visual designers

become useless

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Lecture Overview Introduce ASP.NET data sources Introduce the ASP.NET data bound

controls Show a few SIMPLE examples to get us

started

Slide 4

History of ADO (1) Open Database Connectivity (ODBC)

was created to provide a uniform API to access SQL database servers

OLE DB evolved from ODBC and provided a COM based interface

Next came the first versions of ADO, which encapsulated OLE DB

ADO.NET is the current generation of ADO and uses .NET Managed Providers

Slide 5

History of ADO (2) While not a problem Microsoft has

stepped away from all MSAccess support. The data controls are gone Necessary Jet versions are not usually

installed So we will use SQLServer in this course

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ADO / ASP.NET NOTE The capabilities of ASP and ADO are

vast There are many ways to accomplish the

same task DataReaders vs. DataAdapters DataSource controls vs. manual binding Bound control configuration is

sophisticated

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ADO.NET -The Role of Managed Providers Managed providers interact with a

data source and return data to an application

Data sources are typically (almost always) disconnected After data is returned to the application,

connections are closed

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ADO.NET Namespaces / Classes (Intro) There are many of these Some you don’t need to work with

directly There are many ways to accomplish the

same task

Mastery of the topic requires that you understand what the controls do and how they interact with the underlying classes

Slide 9

ADO.NET Namespaces (1) Here’s the fabric

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

Slide 10

ADO.NET Classes (1) Connection – creates the connection with the

data source (database) Support is provided for ORACLE, SQL Server,

Access, etc. Transaction – allows for transactional

processing Command – typically an SQL statement

executed against a database server Could be a stored procedure

Parameter – a parameter passed to a command

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ADO.NET Classes (2) DataAdapter – a database object that

returns a disconnected set of records (DataSet and DataTable)

DataReader – a forward-only reader to get database records

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Introduction to Connections Executing a database command is generally a

two-step process Create a connection Prepare and execute a command The ASP.NET controls help automate much

of the process There are specific connection classes for OLE

DB, SQL Server and others They all work the same way

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Connection Strings There are tools to build these for you

based on the database provider Connection strings are typically stored

in the web.config file They store all information needed to

establish a database connection More later

Slide 14

Connection Strings (Example) Connection strings are usually stored in

web.config

The following reads the connection string from web.config

Slide 15

Connection Strings (Example) The SqlConnection object represents the

connection itself. It’s properties depict the connection status

Slide 16

Executing Commands(Introduction) Use the SqlCommand object to

Return one record one field (ExecuteNonQuery)

Execute SQL INSERT, UPDATE, DELETE statements

Return records in the form of a DataTable Return records one row at a time

(DataReader)

Slide 17

SqlCommand Object (Using 1 row) The OleDbCommand or SqlCommand

objects work the same way Set the CommandText property to the SQL

statement to execute Set the CommandType property to CommandType.Text

Set the Connection property to an existing Connection object

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SqlCommand Object (Using 1 row) To return one field from one row, call ExecutScalar() on the SqlCommand object

Slide 19

SqlCommand Object (Returning Nothing) Use the ExecuteNonQuery method to

execute SQL statements that do not return values INSERT / UPDATE / DELETE As before, the CommandText property

stores the SQL statement Two ways to do INSERT / UPDATE

/DELETE With parameters Roll the statement by hand

Slide 20

SqlCommand Object (Returning Nothing - Manual) Use create the CommandText, CommandType and Connection as before

The INSERT / UPDATE / DELETE statements get contorted

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SqlCommand Object (Parameters 1 ) Parameters provide the preferred way to

pass data to INSERT / UPDATE / DELETE and other SQL statements

Parameters begin with an @ in the SQL statement

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SqlCommand Object (Parameters 1 ) Then we create the parameters as part

of the command object We are adding items to the parameters

collection

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Using the DataReader This is straight out of the book

There are much better ways to read data but here is the first cut

It’s a forward only reader Call Read to read the first and subsequent

records Create an SqlCommand object as before Call ExecuteReader to initialize Call Read to read each record

Index contains the field name

Slide 24

Using the DataReader (example)

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Reading Multiple Records Here, we use the DataSet and DataTable objects along with the DataAdapter

Steps Create SqlCommand with the SELECT

statement as before Create a new SqlDataAdapter Create a DataSet Call Fill on the DataAdapter to populate

the DataSet

Slide 26

Reading Multiple Records

Slide 27

Introduction to Data Sources Data sources establish the connection

between an ASP.NET application and a database

These are not the same controls as the desktop controls

Slide 28

Data Source Controls(Categories) Tabular

AccessDataSource – For Access databases SqlDataSource – For SQL databases ObjectDataSource – For custom business

objects Hierarchical

SiteMapDataSource – For menus XmlDataSource – To bind XML documents

Slide 29

Data Sources (Core Concepts) The ASP.NET data source controls are bound to

a page rather than the application They belong to System.Web rather than System.Data so they are again unique to ASP.NET

Underneath the hood, there is a DataSet You can use the System.Data classes from an

ASP.NET application Visual Studio does a great job configuring the

data source controls

Slide 30

Data Sources (Under the Hood 1) The Wizards configure properties to

Write SELECT statements and customize them

Write INSERT, UPDATE, and DELETE statements that are executed by other bound controls

Slide 31

Data Sources(Under the Hood 2)

The Properties window tells thetale