Overview of ADO.NET with the.NET Framework Scalable Development, Inc. Building systems today that perform tomorrow.

.NET Experiences  PDC 2000 Build (July 2000).  Visual Studio 1.0 Beta 1 (November 2000).  Book began (January 2001).  Visual Studio 1.0 Beta 2 (June 2001).  First Production ASP.NET App (July 2001).  Production Windows Service (November 2001). Runs today.  4 Production Applications by shipment.  Multiple running applications.

.NET Resources  ASP.NET –  AspAdvice –  Windows Forms –  Architecture – msdn.microsoft.com/architecture .NET News –

Agenda  Design Philosophy  Architectural Overview  Features  When to use What (Code Examples)  Summary

Design Philosophy  Unified Data Story (data, xml, cache objects)  Data is Data; object model is choice  XML objects feel like XML, Data objects feel like Data, Typed Objects feel like objects  Factored components  Explicit model; no black boxes! (Customers/helper code wires together components)  Predictable behaviour, semantics  Optimized performance  Disconnected Relational DataSet  Get Data as fast as possible

Managed Data Overview

What Happened to My RecordSet?  RecordSet  Updateable? Scrollable? Bookmarks? Rowcount? Holding server resources? Cache on client?  DataReader  Connected, non-cached, FO/RO RecordSet  DataSet  Disconnected, cached, scrollable data  DataAdapter  Logic for populating the DataSet and propagating changes back to the datasource

Managed Providers  Manages interaction to a data source  Managed equivalent of OLE DB layer  Directly exposes consumer interfaces  Not a full featured data store interface  Specific to (Optimized for) DataSource  Managed Provider Object Model  Connection  Like ADODB.Connection  Command  Like ADODB.Command  DataReader  Similar to FO/RO ADODB.RecordSet  Fields accessed through strongly typed, indexed accessors

Database Support  System.Data.SQLClient  SQL Server 7  SQL Server 2000  Oracle.DataAccess (ODP.NET).  System.Data.Oracle (MS).  DB2 (only supports.NET 1.0).  MySql.  System.Data.OleDb  System.Data.Odbc ODBC drivers.

Oracle Managed Providers  Microsoft. No support for COM+.  Oracle. Requires Oracle 9iR2 client.

Oracle Support Through OleDb  Microsoft Driver for Oracle. (MsDaOra)  7.x datatypes.  No 8.x datatypes.  Oracle OleDb Driver. (OraOleDb.Oracle)  7.x datatypes.  8.x datatypes.  9.x datatypes.  COM+ challenged.

Oracle Support Through ODBC  Microsoft Driver for Oracle.  Oracle ODBC driver.  Thread challenged.

Oracle Gotchas  Use the latest Oracle SQL Net.  Don’t use COM+ transactions, unless you need them. Info - Oracle is working on an OleDb driver that supports COM+ transactions better.  Always close connections!!!!!!

DataSet Common client data store  Relational View of Data  Tables, Columns, Rows, Constraints, Relations  Directly create metadata and insert data DataSet Tables Table Columns Column Constraints Constraint Rows Row Relations Relation

DataSet Common client data store  Explicit Disconnected Model  Disconnected, remotable object  No knowledge of data source or properties  Common Behaviour  Predictable performance characteristics  Strong Typing  3-D Collection  What to return from a DAL.  Uses DataReader underneath the covers.  Some column metadata is not available.

Data Adapter  Loads a table from a data store and writes changes back.  Exposes two important methods:  Fill(DataSet,DataTable)  Update(DataSet,DataTable)  Provides mappings between tables & columns  User provides insert/update/delete commands  Allows use of Stored Procedures  CommandBuilder component available (not used much in ASP.NET)  Allows single DataSet to be populated from multiple different datasources

ADO.NET and XML  The DataSet  Loads/saves XML data into/out of DataSet  Schema can be loaded/saved as XSD  Schema can be inferred from XML Data  The DataSet can be associated with an XmlDataDocument  Exposes a relational view over structured XML  According to the DataSet schema  Allows strong typing, control binding, relational access of XML data  Allows XML tools (schema validation, XSL/T, XPath queries) against relational data  Preserves full fidelity of XML Document

When to use What  Connected Data Access  Code Examples:  Retrieving Results  Insert, Update, and Delete.  Disconnected Data Access  Code Examples:  Application Data  Loading XML  Client Cursor Updating  XML View of Relational Data  Code Example:  SQLXML  XML Manipulations

Connected Data Access  Connected Data Access - Managed Providers  Connection, Transaction  Connecting to DataSource  Starting/Ending Transactions  Command, Parameters  Database Updates, Selects, DDL  DataReader  (FO/RO) Server Cursor  DataAdapter  Pushing data into Dataset  Reading changes out of DataSet

Code: Retrieving Results ‘Create and open an OleDbConnection Dim OleDbCn as new OleDbConnection(“……”) OleDbCn.Open() ‘Create and execute OleDbCommand Dim OleDbCmd as new OleDbCommand("Select * from authors where...", OleDbCn) Dim dr as DataReader dr = OleDbCmd.ExecuteReader() ‘Retrieve Results while(dr.Read()) Console.WriteLine("Name = " + dr("au_lname“)) End while dr.Close() OleDbCn.Close() ‘This is VERY IMPORTANT

Disconnected Data Access  Disconnected Data Access - DataSet  Application Data  Remoting Results  SOAP, WebMethods, Remoting  Caching Results  ASP.NET Cache  Persisting results  Save Data as XML, Schema as XSD  User interaction  Scrolling, sorting, filtering  DataView, DataViewManager  Binding Windows controls

Code: Application Data ‘ Create an "Inventory" Table Dim ds as new DataSet() Dim inventory as new DataTable("Inventory") inventory.Columns.Add("TitleID",typeof(Int32)) inventory.Columns.Add("Quantity",typeof(Int32)) ds.Tables.Add(inventory) ‘ Add a record to the Inventory table Dim row as inventory.NewRow() Row("TitleID“)=1 Row("Quantity“)=25 inventory.Rows.Add(row)

Code: Loading XML ‘Load DataSet with XML Dim ds as new DataSet() ds.ReadXml("inventory.xml") ‘Add a record to the Inventory table Dim inventory as new DataTable = ds.Tables("Inventory“) Dim row as DataRow = inventory.NewRow() Row("TitleID“)=1 Row("Quantity“)=25 inventory.Rows.Add(row) ‘Write out XML ds.WriteXml("updatedinventory.xml")

Code: Insert/Update/Delete Dim OleDbCn as new OleDbConnection(“…….”) Dim OleDbCM as new OleDbCommand( “Insert/Update/Delete Command“, OleDbCn) OleDbCn.Open() OleDbCm.ExecuteNonQuery() If OleDbCn.State <> ConnectionState.StateClosed then OleDbCn.Close() End if OleDbCn = Nothing ‘Old habits die hard

Code: Client Cursor Updating (easy) ‘Populate DataSet Dim OleDbDA as new OleDbDataAdapter( "Select * from customers“, OleDbCn); Dim ds as new Dataset() OleDbDA.MissingSchemaAction = MissingSchemaAction.AddWithKey OleDbDA.Fill(ds, "Customer") ‘Find customer w/PK value of 256 Dim dr as DataRow = ds.Tables("Customer“).Rows.Find(256) ‘Change LastName Dr("LastName“) = "Smith" ‘Update DataBase Dim OleDbCb as new OleDbCommandBuilder = OleDbCommandBuilder(da) OleDbDa.Update(ds, "Customer")

Code: Client Cursor Operations (harder) ‘Populate DataSet Dim OleDbDA as new OleDbDataAdapter( "Select customerId, customerName from customers“, OleDbCn); Dim ds as new Dataset() Dim dr as DataRow OleDbDA.Fill(ds, "Customer") OleDbDA.InsertCommand = new OleDbCommand(“insert into customers (CustomerName) values OleDbCn) dr = ds.Tables(“Customer”).NewRow() ‘Add Customer Name Dr("Customer Name“) = "Fred's Company" ‘Update DataBase ds.Tables(“Customer”).Rows.Add(dr) OleDbDA.Update(ds, “Customer”)

Notes on the Client Cursor Update  Individual commands are sent.  Can be wrapped in a transaction.  CommandBuilder is “relatively” inefficient.

Code: Manual Transaction Dim OleDbCM as new OleDbCommand( “Insert/Update/Delete Command“, OleDbCn) Dim OleDbTx as OleDbTransaction OleDbTx = OleDbCn.BeginTransaction(Isolation.ReadUncommitted) OleDbCm.Transaction = OleDbTx Try OleDbCn.Open() OleDbCm.ExecuteNonQuery() OleDbTx.Commit() Catch exc as Exception OleDbTx.RollBack() Throw( new Exception( “Error Occurred”, exc.InnerException ) Finally If OleDbCn.State <> ConnectionState.StateClosed then OleDbCn.Close() End if End Try OleDbCn = Nothing

Cleanup  Close your connection objects and return them to the connection pool.  Dispose all objects. Don't wait on the finalizer.

Great, Now What’s Missing?  Server-side scrollable cursor support. (not an issue for Oracle)  Complete column information.  ADOX.Catalog type of support. No support for creating tables, columns, users, indexes, ……..

ADO Classic in.NET  Works.  Can continue to use it.  Required for ADOX support.

Summary  ADO.NET is…  Optimized for Data Access.  Managed Providers for connected access  DataSet for disconnected, user interaction  DataReader for connected RO use.  Open Architecture  No Black Boxes  Tightly Integrated with XML  DataSet reads/writes XML  XmlDataDocument integrates relational and XML views

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