Prentice Hall © 2004 1 COS 346 Day 21. 7-2 Agenda Capstone Progress report due Assignment 9 not corrected yet Assignment 10 posted (last one!!!) –Due.

COS 346

Day 21Day 21

Agenda

• Capstone Progress report due• Assignment 9 not corrected yet • Assignment 10 posted (last one!!!)

– Due April 27 @ 2 PM– Lowest Assignment score will be dropped

• XML and ADO.NET on April 23• Quiz 3 on April 27

– SQL Chap 8-11– DP Chaps 8, 9, 11, 12 and 13– 20 M/C @ 4 points each– 4 short essays @ 5 points each– 60 mins, Open book, Open notes

• Capstones Due on April 27 • Discussion on Database Access Standards

David M. Kroenke’s

Chapter Twelve:

ODBC, OLE DB, ADO, and ASP

Part One

Database Processing:Fundamentals, Design, and Implementation

Introduction

• Because database applications today reside in a complicated environment, various standards have been developed for accessing database servers.

• Some of the important standards are– OBDC (Open Database Connectivity) is the early standard for

relational databases.– OLE DB is Microsoft’s object-oriented interface for relational and

other databases.– ADO (Active Data Objects) is Microsoft’s standard providing

easier access to OLE DB data for the non-object-oriented programmer.

The Web Server Data Environment

• A Web server needs to publish applications that involve different data types.

The Role of the ODBC Standard

The Role of ODE DB

The Role of ADO

Open Database Connectivity (OBDC)

• The Open Database Connectivity (ODBC) standard provides a DBMS-independent means for processing relational database data.

• It was developed in the early 1990s by an industry committee and has been implemented by Microsoft and many other vendors.

• The goal is to allow a developer to create a single application that can access databases supported by different DBMS products without needing to be changed or recompiled.

ODBC Architecture

OBDC Components (Continued)

• OBDC consists of a data source, an application program, a driver manager, and a DBMS driver.

• A data source is the database and its associated DBMS, operating system, and network platform.– An ODBC data source can be a relational database, a

file server, or a spreadsheet.

• An applications program issues requests to create a connection with a data source.

OBDC Components

• A driver manager determines the type of DBMS for a given ODBC data source and loads that driver in memory.

• A DBMS driver processes ODBC requests and submits specific SQL statements to a given type of data source.– A single-tier driver processes both ODBC calls and

SQL statements.– A multiple-tier driver processes ODBC calls, but

passes the SQL requests to the database server.

ODBC Driver Types:ODBC Single-Tier Driver

ODBC Driver Types:ODBC Multiple-Tier Driver

Conformance Levels

• Levels of conformance balance the scope of the OBDC standard.

• There are two types of conformance levels:– ODBC conformance levels concern the features and

functions that are made available through the driver’s application program interface (API).

• A driver API is a set of functions that the application can call to receive services.

– SQL conformance levels specify which SQL statements, expressions, and data types a driver can process.

Summary ofOBDC Conformance Levels

(Continued)

Summary ofSQL Conformance Levels

(Continued)

ODBC Data Sources

• A data source is an ODBC data structure that identifies a database and the DBMS that processes it.

• Three types of data source names:– A file data source is a file that can be shared among database

users having the same DBMS driver and privilege.– A system data source is local to a single computer and may be

used by the operating system and any user on that system.• System data sources are recommended for Web servers.• To define a system data source name, the type of driver and the

database need to be specified.

– A user data source is available only to the user who created it.

Creating a System Data Source:Selecting the Oracle Driver

Creating a System Data Source:Setting Data Source Properties

David M. Kroenke’s Database Processing

Fundamentals, Design, and Implementation

(10th Edition)

End of Presentation:Chapter Twelve Part One

David M. Kroenke’s

Chapter Twelve:

ODBC, OLE DB, ADO, and ASP

Part Two

Database Processing:Fundamentals, Design, and Implementation

OLE DB

• OLE DB is an implementation of the Microsoft OLE object standard.– OLE DB objects are COM objects and support all required

interfaces for such objects.

• OLE DB breaks the features and functions of a DBMS into COM objects, making it easier for vendors to implement portions of functionality.– This characteristic overcomes a major disadvantage of ODBC.– With ODBC, a vendor must create an ODBC driver for almost all

DBMS features and functions in order to participate in ODBC at all.

Object-Oriented Concepts

• An object-oriented programming object is an abstraction that is defined by its properties and methods.– An abstraction is a generalization of something.– A property specifies set of characteristics of an

object.– A method refers to actions that an object can

perform.– A collection is an object that contains a group of

other objects.

OLE DB Goals

• Create object interfaces for DBMS functionality pieces:– Query, update, transaction management, etc.

• Increase flexibility:– Allow data consumers to use only the objects they need.– Allow data providers to expose pieces of DBMS functionality.– Providers can deliver functionality in multiple interfaces.– Interfaces are standardized and extensible.

• Provide object interfaces over any type of data:– Relational and non-relational database, ODBC or native, VSAM

and other files, Email, etc.

• Do not force data to be converted or moved from where it is.

OLE DB Basic Constructs

• There are data consumers and data providers:– Data consumers - Users of OLE DB functionality.– Data providers - Sources of OLE DB functionality.

• An interface is a set of objects and the properties and methods they expose in that interface:– Objects may expose different properties and methods in different

interfaces.

• An implementation is how an object accomplishes its tasks:– Implementations are hidden from the outside world and may be

changed without impacting the users of the objects.

OLE DB Terminology:Data Providers

• A rowset is equivalent to a cursor.

• OLE DB has two types of data providers: – Tabular data provider — exposes data via rowsets.

• Examples: DBMS, spreadsheets, ISAMs (file processors), email.

– Service provider — a transformer of data through OLE DB interfaces.

• It is both a consumer and a provider of transformed data.• Examples: query processors, XML document creator.

Rowset Interfaces

Active Data Objects (ADO)

• Active Data Objects (ADO) characteristics:– A simple object model for OLE DB data consumers– It can be used from VBScript, JScript, Visual Basic,

Java, C#, C++– It is a single Microsoft data access standard– Data access objects are the same for all types of OLE

DB data

Invoking ADO from Active Server Pages

• In Microsoft’s Active Server Pages (ASP) are Web pages where:– Statements are enclosed within the

characters <% . . .%>.– ASP statements are processed on the Web

server.– Other (HTML) statements are processed by

the client Web browser.

The ADO Object Model

Connection Object

• A connection object establishes a connection to a data provider and data source.– Connections have an isolation mode.

• Once a connection is created, it can be used to create RecordSet and Command objects.

RecordSet Objects

• RecordSet objects represent cursors:– They have both CursorType and LockType properties.– RecordSets can be created with SQL statements.– The Fields collection of a RecordSet can be

processed to individually manipulate fields.– The Errors collection contains one or more error

messages that result from an ADO operation.

Command Object

• The command object is used to execute stored parameterized queries or stored procedures:– Input data can be sent to the correct ASP

using the HTML FORM tag.– Table updates are made using the RecordSet

Update method.

ADO Constants:Isolation Levels

ADO Constants:Cursor Levels

ADO Constants:Lock Types

Connection Object:ASP Code

Dim objConn

Set objConn = Server.CreateObject (“ADODB.connection”)

objConn.IsolationLevel = adXactReadCommitted

‘ use ADOVBS

objConn.Open “ViewRidgeSS”,

objConn.Open “DSN=ViewRidgeOracle2;UID=DK1;PWD=Sesame”

http://www.flb.fo/infolit/ADOVBS.INC

RecordSet Object:ASP Code

Dim objRecordSet, varSql

varSQL = “SELECT * FROM ARTIST”

Set objRecordSet = Server.CreateObject(“ADODB.Recordset”)

objRecordSet.CursorTye = adOpenStatic

objRecordSet.LockType = adLockReadOnly

objRecordSet.Open varSQL, objConn

Fields Collection:ASP Code

Dim varI, varNumCols, objField

varNumCols = objRecordSet.Fields.Count

For varI = 0 to varNumCols - 1

Set objField = objRecordSet.Fields(varI)

‘ objField.Name now has the name of the field

‘ objField.Value now has the value of the field

‘ can do something with them here

Errors Collection:ASP Code

Dim varI, varErrorCount, objError

On Error Resume Next

varErrorCount = objConn.Errors.Count

If varErrorCount > 0 Then

For varI = 0 to varErrorCount - 1

Set objError = objConn.Errors(varI)

‘ objError.Description contains

‘ a description of the error

End If

Command Object:ASP Code

Dim objCommand, objParam, objRs

‘Create the Command object, connect it to objConn and set its format

Set objCommand = Server.CreateObject(“ADODB.command”)

Set objCommand.ActiveConnection = objConn

objCommand.CommandText=“{call FindArtist (?)}”

‘Set up the parameter with the necessary value

Set objParam = objCommand.CreateParameter (“Nationality”, adChar, adParamInput, 25)

objCommand.Parameters.Append objParam

objParam.Value = “Spanish”

‘Fire the Stored Proc

Set objRs = objCommand.Execute

ADO Example: Reading a

Artist.asp

ADO Example: Reading a TableThe Artist.asp Results

David M. Kroenke’s Database Processing

Fundamentals, Design, and Implementation

(10th Edition)

End of Presentation:Chapter Twelve Part Two

Prentice Hall © 2004 1 COS 346 Day 21. 7-2 Agenda Capstone Progress report due Assignment 9 not corrected yet Assignment 10 posted (last one!!!) –Due.

kroenkes database processing

database applications

pearson prentice hall

database servers

database access standards

odbc standard slide

db data

odbc architecture slide

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