1. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-1 David M. Kroenke’s Chapter Twelve: ODBC, OLE DB, ADO, and ASP Part Two Database Processing: Fundamentals, Design, and Implementation

2. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-2 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.

3. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-3 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.

4. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-4 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.

5. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-5 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.

6. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-6 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, 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.

7. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-7 Rowset Interfaces

8. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-8 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

9. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-9 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.

10. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-10 The ADO Object Model

11. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-11 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.

12. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-12 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.

13. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-13 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.

14. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-14 ADO Constants: Isolation Levels

15. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-15 ADO Constants: Cursor Levels

16. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-16 ADO Constants: Lock Types

17. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-17 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” %>

18. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-18 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 %>

19. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-19 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 Next >%

20. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-20 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 Next End If >%

21. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-21 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 >%

22. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-22 ADO Example: Reading a Table Artist.asp

23. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-23 ADO Example: Reading a Table The Artist.asp Results

24. DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall 12-24 David M. Kroenke’s Database Processing Fundamentals, Design, and Implementation (10 th Edition) End of Presentation: Chapter Twelve Part Two