04 | Data Acess Technologies Bruno Terkaly | Technical Evangelist Bret Stateham | Technical Evangelist

Module Overview ADO.NET LINQ (Language Integrated Query) XML (Extensible Markup Language) LINQ to XML

ADO.NET

Basic ADO.NET Objects Connection* DataReader* Command* (SELECT, …) Results string constr = "Server=server;Database=db;User ID=user;Password=pwd;..."; using(SqlConnection connection = new SqlConnection(constr)) { string query = "SELECT TOP 10 PositionID, ReportedAt, Latitude, Longitude FROM dbo.Positions;"; using (SqlCommand cmd = new SqlCommand(query,connection)) { connection.Open(); using (SqlDataReader rdr = command.ExecuteReader()) while(rdr.Read()) string position = string.Format("{0},{1},{2},{3}",rdr.GetInt32(0),rdr.GetDateTime(1),rdr.GetFloat(2),rdr.GetFloat(3)); Console.WriteLine(position); } * ADO.NET Provider Specific: SqlConnection, SqlCommand, SqlDataReader

ADO.NET Providers

DataTable and DataAdapter Connection* DataTable DataAdapter* Fill() SelectCommand* Update() InsertCommand* UpdateCommand* DeleteCommand* * ADO.NET Provider Specific: SqlConnection, SqlCommand, SqlDataAdapter

DataSets Connection* DataSet DataAdapter(s)* Commands* Fill/Update * ADO.NET Provider Specific: SqlConnection, SqlCommand, SqlDataAdapter

Querying data with ADO.NET

LINQ (Language-INtegrated Query)

Data Sources & Client Access Relational DBs XML Collections ADO.NET / SQL DOM / XPath C#

LINQ to Objects & IEnumerable LINQ to the Rescue! Relational DBs XML Collections LINQ LINQ to Entities & IQueryable LINQ to XML LINQ to Objects & IEnumerable C#

What is LINQ? A way to query data in memory A collection of extension methods to IEnumerable Queries are “composable” and don’t execute until data is accessed. Allows querying, filtering, aggregating, joining, collections in memory A way to ship queries across application layers IQueryable represents the intention of the query Can be shipped between application tiers (service <> client) Service can provide the initial query Client can further “compose” the query (filter, sort, etc) Client passes the composed query back to the service The service returns the data as specified by the query. Cool!

LINQ to Objects

XML (Extensible Markup Language)

Good Old XML Read all about it: www.w3.org/xml (seriously) <Positions> <Position PositionID="1"> <ReportedAt>2008-11-10T22:51:00</ReportedAt> <Region>North Carolina</Region> <Country>United States</Country> <Latitude>35.06615067</Latitude> <Longitude>-76.96884918</Longitude> </Position> <Position PositionID="2"> <ReportedAt>2008-11-13T22:54:00</ReportedAt> <Latitude>35.06611633</Latitude> <Longitude>-76.96875000</Longitude> <Position PositionID="3"> <ReportedAt>2008-11-15T17:17:00</ReportedAt> <Latitude>35.06600189</Latitude> <!-- ... --> </Positions> Read all about it: www.w3.org/xml (seriously) Family of related standards XML XML Schemas XPath XQuery XSLT (Transformations) XSL-FO …

Working with XML in Code System.Xml XmlDocument for Document Object Model (DOM) based operations XmlReader for SAX (streaming) based operations Create XML with XmlDocument, XmlElement, XmlAttribute… Can save / load XML from files Can parse XML from strings

System.Xml Namespace XmlDocument XmlDeclaration XmlComment XmlElement <?xml version="1.0" ?> <!– Sample Position --> <Position>…</Position> <Position PositionID="1"> <Latitude> 35.06615067 </Latitude> <Longitude> -76.96884918 </Longitude> </Position> </Positions> XmlDocument XmlDeclaration XmlComment XmlElement XmlAttribute XmlText XmlNode

DOM Based XML Processing

LINQ to XML

LINQ to Objects & IEnumerable LINQ to the Rescue! Relational DBs XML Collections LINQ LINQ to Entities & IQueryable LINQ to XML LINQ to Objects & IEnumerable C#

System.Xml.Linq Namespace XDocument <?xml version="1.0" ?> <!– Sample Position --> <Position>…</Position> <Position PositionID="1"> <Latitude> 35.06615067 </Latitude> <Longitude> -76.96884918 </Longitude> </Position> </Positions> XDeclaration XComment XElement XAttribute XText

LINQ to XML