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Information about ADO Net

Published on October 24, 2007

Author: Breezy


Introduction to ADO.Net:  Introduction to ADO.Net Malek Kemmou CEO Arrabeta bioAdapter.Fill(bio_DataSet); repeater1.DataBind();:  bioAdapter.Fill(bio_DataSet); repeater1.DataBind(); CEO Arrabeta (consulting firm based in Casablanca Morocco) Newtelligence Alliance Partner Senior Consultant and Senior Trainer Solutions Architecture, integration, interoperability Microsoft Regional Director for Middle East and Africa Ineta MEA Speaker Bureau Speaker at many conferences and events (TechEd, NDC, MDC, DevDays, DevEssentials …) Agenda:  Agenda Overview of Data Access in .Net Fetching Data Processing Data Data as XML Tips & Tricks What is ADO.NET?:  What is ADO.NET? Managed Code (.NET) Data Access Methodology Complete Integration with the .NET Framework Improved support for the disconnected business model Improved integration with XML Explicit control of Data Access behaviors for .NET applications Introducing ADO.NET:  Introducing ADO.NET Part of the .NET framework, ADO.NET was built with the new world of XML, disconnected data, web and HTTP in mind Is a rewrite of ADO for the .NET framework Not a replacement of ADO for COM developers ADO.NET is a natural evolution of ADO, built around n-tier development and architected with XML at its core Overview of Data in .Net:  Overview of Data in .Net .NET Data Provider DataReader Command Connection Fetching Data:  Fetching Data Connected Model Create a connection Open Connection Execute Commands Obtain Results Process Rows Close Connection Data Bind Create & open a Connection:  Create & open a Connection C# SqlConnection cnn = new SqlConnection(“Data Source = MyServer; User Id=myUser; password=myPassword”); cnn.Open(); VB.Net Dim cnn as New SqlConnection((“Data Source = MyServer; User Id=myUser; password=myPassword”) Open a Transaction if needed:  Open a Transaction if needed C# SqlTransaction tnx = cnn.BeginTransaction(); // do some Data Access and processing If (somecondition) tnx.Commit(); Else tnx.Rollback(); VB.Net Dim tnx as SqlTransaction = cnn.BeginTransaction ‘ Do some Data Access and processing If (somecondition) Then tnx.Commit() Else tnx.Rollback() End If Execute Commands:  Execute Commands Various types of commands Insert, Update, Delete, stored procedure, … Optionally transmit parameters SqlCommand cmd = new SqlCommand("DeleteAccount", cnn); cmd.CommandType = CommandType.StoredProcedure; SqlParameter param = new SqlParameter("@A_ID",typeof(string)); param.Value = accountID; cmd.Parameters.Add(param); Int32 RowsAffected = cmd.ExecuteNonQuery(); Obtain a Single Value:  Obtain a Single Value Use ExecuteScalar SqlCommand cmd = new SqlCommand( "Select Balance from Accounts where ” + “AccountID = @A_ID", &cnn); cmd.Parameters.Add("@A_ID",accountID); Decimal AccountBalance = (Decimal) cmd.ExecuteScalar(); Process Rows:  Process Rows Dynamic Processing SqlCommand cmd = new SqlCommand("Select Desc, " +"Amt from Activity where AccountID = @A_ID", cnn); cmd.Parameters.Add("@A_ID",accountID); SqlDataReader results = cmd.ExecuteReader(); While (results.Read()) { Console.Write("Description: " + results.GetString(0)); Console.WriteLine("Amount: " + results.GetDecimal(1)); } Data Binding (Web Forms):  Data Binding (Web Forms) public void Page_Load(Object sender, EventArgs e) { // Créer une SqlCommand et obtenir un DataReader SqlConnection cnn = new SqlConnection("server=localhost;uid=sa;"); cnn.Open(); SqlCommand cmd = new SqlCommand("Select * from customers", cnn); SqlDataReader results = cmd.ExecuteReader(); // Lier les résulats ActivityList.DataSource = results; ActivityList.DataBind(); } Demo:  Demo Connected DataAccess from a Web Page Processing Data:  Processing Data Disconnected Model Fill DataSet Navigate the DataSet Update Changes from DataSet Data Bind DataSet can be used as cache DataSet:  DataSet A DataSet is a local buffer of tables, or a collection of disconnected “recordsets” Keeps track of the relationships between the tables it contains DataSets are an in-memory relational store Exposes a rich programming model All data is stored in a local cache Same performance and semantics regardless of whether the data is loaded from a database, loaded from XML, or is generated by the application. No connection! (Not directly anyway) DataSets: Tables:  DataSets: Tables A DataSet contains a collection of DataTables (the DataTableCollection) A DataTable represents one table of in-memory data. It contains a collection of columns (the DataColumnCollection) that represents the table's schema A DataTable also contains a collection of rows (the DataRowCollection), representing the data held by the table. It remembers the original state along with current state, tracking the kinds of changes that have occurred. Fill DataSet from Database:  Fill DataSet from Database Use a DataAdapter SqlCommand selectCommand = new SqlCommand("Select CategoryName from Categories",cnn); SqlDataAdapter adapter = new SqlDataAdapter(); adapter.SelectCommand = selectCommand; DataSet categories = new DataSet("Categories"); adapter.Fill(categories); Navigate the DataSet:  Navigate the DataSet Navigate the Row Collection of a Table Obtain Rows as an Array Use language expressions as “foreach” foreach(DataRow customer in myDataSet.Tables["Customer"].Rows) { Console.WriteLine("Orders for customer: " + customer["Name"]); foreach(DataRow order in customer.GetChildRows("cust_orders") ) { Console.Write("\t Order ID = " + order["OrderID"]); Console.WriteLine("Amount = " + order["Amount"]); } } Update Changes:  Update Changes SqlDataAdapter adapter = new SqlDataAdapter(); SqlCommand delete = new SqlCommand("DeleteOrder",cnn); delete.CommandType=CommandType.StoredProcedure; delete.Parameters.Add("@OrderID",typeof(Int32)).SourceColumn="OrderID"; adapter.DeleteCommand = delete; SqlCommand insert = new SqlCommand("AddOrder",cnn); insert.CommandType=CommandType.StoredProcedure; insert.Parameters.Add("@OrderID",typeof(Int32)).SourceColumn="OrderID"; insert.Parameters.Add("@CustD",typeof(Int32)).SourceColumn="CustomerID"; insert.Parameters.Add("@Date",typeof(DateTime)).Value = DateTime.Now; adapter.InsertCommand = insert; SqlCommand update = new SqlCommand("UpdateOrder",cnn); update.CommandType=CommandType.StoredProcedure; update.Parameters.Add("@OrderID",typeof(Int32)).SourceColumn="OrderID"; update.Parameters.Add("@CustD",typeof(Int32)).SourceColumn="CustomerID"; adapter.UpdateCommand = update; adapter.Update(ordersTable); Winforms DataBinding:  Winforms DataBinding SqlCommand cmd = new SqlCommand("GetAccountInfo", cnn); cmd.CommandType=CommandType.StoredProcedure; cmd.Parameters.Add("@A_ID",accountID); DataSet account = new DataSet; DataAdapter adapter = new DataAdapter(cmd); adapter.Fill(account); DataGrid accountGrid = new DataGrid(); accountGrid.SetDataBinding(myDataSet, "AccountList"); Demo:  Demo A Simple WinForm Working with Data ADO .NET & XML:  ADO .NET & XML DataSets and XML Load/Save XML Data to/From DataSet Schema can be loaded/saved as XSD Schema can be inferred from XML Data Loading XML:  Loading XML DataSet ds = new DataSet(); ds.ReadXml("inventory.xml"); DataTable inventory = ds.Tables["Inventory"]; DataRow row = inventory.NewRow(); row["TitleID"]=1; row["Quantity"]=25; inventory.Rows.Add(row); ds.WriteXml("updatedinventory.xml"); Load Schema from XSD:  Load Schema from XSD myDataSet.ReadXmlSchema(schemaFile); Complex Types converted to tables Nested Complex Types converted to child tables Keys/Constraints converted into unique constraints Foreign Key Constraints inferred Inferred Schema:  Inferred Schema If no schema is defined before calling DataSet.ReadXml(), schema is inferred from data General Rules An element becomes a table if : It is repetitive within its parent or it contains more than one simple content …Otherwise, it becomes a column Attributes become columns Relations are created for nested tables Hidden columns are created for the keys Useful for dynamic data binding Demo:  Demo DataSets and XML X/Path And XSL/T Over DataSet:  X/Path And XSL/T Over DataSet XmlDataDocument xmlData = new XmlDataDocument(po); // Requête X/Path XmlNodeList nodes = xmlData.SelectNodes("//Item[@qty>100]"); foreach(XmlNode node in nodes) { DataRow row = xmlData.GetRowFromElement((XmlElement)node); row.Delete(); } // Transformation XSLT XslTransform xsltransform = new XslTransform(); xsltransform.Load("po.xsl"); XmlReader xReader = xsltransform.Transform(xmlData, null); Tips & Tricks:  Tips & Tricks Auto generate Commands for updating DataSet Refreshing DataSet data Managing and processing errors when updating a DataSet Working with row versions and changes Passing null values Guarantee connection closes when DataReader is finished Inserting primary keys Auto Generate Commands for Updating DataSet:  Auto Generate Commands for Updating DataSet Use CommandBuilder SqlDataAdapter sda = new SqlDataAdapter(“select x, y, z from table1”, cnn); SqlCommandBuilder scb = new SqlCommandBuilder(sda); sda.UpdateCommand = scb.GetUpdateCommand(); sda.InsertCommand = scb.GetInsertCommand(); sda.DeleteCommand = scb.GetDeleteCommand(); sda.Update(ds); Refreshing DataSet Data:  Refreshing DataSet Data Fill data with the Fill method of the Adapter myAdapter1.fill(dataSet12); Process data. Before Updating, use : DataSet dataSetTemp = new DataSet(); myAdapter1.fill(dataSetTemp); dataSet12.Merge(dataSetTemp, true); Managing and Processing Errors When updating DataSet:  Managing and Processing Errors When updating DataSet DataAdapter.ContinueUpdateOnError Default is False; setting to True allows all updates to complete even if updates on certain rows generate errors DataTable.GetErrors() Returns array of DataRow objects that represent rows whose updates failed DataRow.RowError Returns a string with a general error message that applies to the entire row DataRow.GetColumnsInError() Returns array of DataColumn objects that contributed to error DataRow.GetColumnError(x) Returns string description of the error itself x is column ordinal, name, or DataColumn object Working with Row versions and changes:  Working with Row versions and changes Item(x) Allows you to examine the value of column x, where x is column’s ordinal or name Item(x, version) Allows you to examine the value of a specific version of column x (DataRowVersion.Current, .Default, .Original, or .Proposed) BeginEdit(), EndEdit() In conjunction with .Items(x), allows you to modify column values in the row CancelEdit() Abandons pending changes to an edited row RowState DataRowState.Added, .Deleted, .Detached, .Modified, or .Unchanged Passing null values:  Passing null values Use DBNull.Value SqlParameter param = new SqlParameter(); param.Value = DBNull.value; Guarantee connection closes when DataReader finishes:  Guarantee connection closes when DataReader finishes Use CommandBehavior.CloseConnection private DataReader getCategories() { SqlCommand cmd = new SqlCommand( "Select * from Categories, cnn); DataReader results = cmd.ExecuteReader(CommandBehavior.CloseConnection); return results; } Inserting Primary Keys:  Inserting Primary Keys Use Guids as Primary Keys Can be generated on the client Guarantees to be unique Doesn’t change when updated on the server No problem on child tables Summary:  Summary ADO.Net has tailored objects .NET Data Providers for connected access Executing commands DataReader DataSet for disconnected access, user interaction and caching ADO.Net and XML are made for each other Questions:  Questions I will post session content on my blog :

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