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1、02:26:41,1,任务3 LINQ应用,实训1LINQ的基本概念 实训2LINQ to Objects 实训3LINQ to XML 实训4LINQ to DataSet 实训5LINQ to SQL 实训6LINQ标准查询运算符,02:26:41,2,实训1LINQ的基本概念,LINQ的基本架构 LINQ表达式是强类型的,02:26:41,3,LINQ的基本架构,02:26:41,4,实训1LINQ的基本概念,LINQ表达式是强类型的,02:26:41,5,实训2LINQ to Objects,创建一个控制台应用项目 查询一个整数列表 查询一个对象列表,02:26:41,6,创建一个控制
2、台应用项目,02:26:41,7,查询一个整数列表,1: class Program 2: 3: static void Main(string args) 4: 5: NumQuery(); 6: 7:,02:26:41,8,查询一个整数列表,8: static void NumQuery() 9: 10: var numbers = new int 1,4,9,16,25,36 ; 11: 12: var evenNumbers = from p in numbers where (p % 2) = 0 select p; 13: Console.WriteLine(“Results:“)
3、; 14: foreach (var val in evenNumbers) 15: Console.WriteLine(val); 16: 17: ,02:26:41,9,查询一个对象列表,1: public class Customer 2: 3: public string CustomerID get; set; 4: public string City get; set; 5: 6: public override string ToString() 7: 8: return CustomerID + “t“ + City; 9: ,02:26:41,10,实训3LINQ to X
4、ML,读取XML文档 查询XML文档 转换XML文档,02:26:41,11,读取XML文档,1: 2: 3: 4: 5: 6: 7: 8: 9: 10: 11: ,02:26:41,12,读取XML文档,1: static IEnumerable CreateCustomers() 2: 3: var results=from c in XDocument.Load(“Customers.xml“) .Descendants(“Customers“).Descendants() select new Customer City = c.Attribute(“City“).Value, Cus
5、tomerID = c.Attribute(“CustomerID“).Value ; 4: return results; 5: ,02:26:41,13,查询XML文档,1: static void Main(string args) 2: 3: XMLQuery(); 4: 5: 6: public static void XMLQuery() 7: 8: var doc = XDocument.Load(“Customers.xml“); 9: Console.WriteLine(“XML Document:n0“, doc); 10: ,02:26:41,14,转换XML文档,1:
6、public static void XMLQuery() 2: 3: XDocument doc = XDocument.Load(“Customers.xml“); 4: var results = from c in doc.Descendants(“Customer“) where c.Attribute(“City“).Value = “London“ select c; 5: XElement transformedResults = new XElement(“Londoners“, from customer in results select new XElement(“Co
7、ntact“, new XAttribute(“ID“, customer.Attribute(“CustomerID“).Value), new XElement(“Name“, customer.Attribute(“ContactName“).Value), new XElement(“City“, customer.Attribute(“City“).Value); 6: Console.WriteLine(“Results:n0“, transformedResults); 7: ,02:26:41,15,实训4LINQ to DataSet,创建数据集 LINQ查询DataSet数
8、据集,02:26:41,16,创建数据集,02:26:41,17,创建数据集,02:26:41,18,创建数据集,02:26:41,19,LINQ查询DataSet数据集,1: static NorthwindDS.CustomersDataTable CreateCustomers() 2: 3: string sqlCommand=“select * from customers“; 4: string sqlConnection=ConfigurationManager.ConnectionStrings “LINQtoDataSet.Properties.Settings.Northw
9、indConnectionString“. ConnectionString; 5: SqlDataAdapter adapter=new SqlDataAdapter(sqlCommand , sqlConnection ); 6: NorthwindDS.CustomersDataTable table = new NorthwindDS.CustomersDataTable(); 7: adapter.Fill(table); 8: 9: return table; 10: ,02:26:41,20,实训5LINQ to SQL,创建对象、关系映射 数据查询 数据修改 调用存储过程 数据
10、排序、分组,02:26:41,21,创建对象、关系映射,02:26:41,22,创建对象、关系映射,02:26:41,23,数据查询,1: static void ObjectQuery() 2: 3: var db=new NorthwindDataContext(); 4: var results = from c in db.Customers where c.City = “London“ select c; 5: foreach (var c in results) 6: Console.WriteLine(“0t1“,c.CustomerID,c.City ); 7: ,02:26
11、:41,24,数据查询,1: static void ObjectQuery2() 2: 3: var db=new NorthwindDataContext(); 4: var results = from c in db.Customers from o in db.Orders where c.City = “London“ select new c.ContactName,o.OrderID ; 5: foreach (var c in results) 6: Console.WriteLine(“0t1“, c.ContactName , c.OrderID ); 7: ,02:26
12、:41,25,数据修改,1: static void ModifyData() 2: 3: var db = new NorthwindDataContext(); 4: int count = db.Customers. Where(c = c.CustomerID = “ADVCA“).Count(); 5: Console.WriteLine(“Number created before: 0“,count.ToString () ); 6: 7: var newCustomer = new Customers CompanyName =“AdventureWorks Cafe“, Cu
13、stomerID =“ADVCA“ ; 8: db.Customers.InsertOnSubmit(newCustomer); 9: db.SubmitChanges(); 10: 11: count = db.Customers.Where(c = c.CustomerID = “ADVCA“).Count(); 12: Console.WriteLine(“Number created after: 0“, count.ToString(); 13: ,02:26:41,26,数据修改,1: static void ModifyData2() 2: 3: var db = new Nor
14、thwindDataContext(); 4: int count = db.Customers. Where(c = c.ContactName = “New Contact“).Count(); 5: Console.WriteLine(“Data updated before: 0“, count.ToString(); 6: 7: var existingCustomer = db.Customers.First(); 8: existingCustomer.ContactName = “New Contact“; 9: db.SubmitChanges(); 10: 11: coun
15、t = db.Customers. Where(c = c.ContactName = “New Contact“).Count(); 12: Console.WriteLine(“Data updated after: 0“, count.ToString(); 13: ,02:26:41,27,调用存储过程,1: static void CallSproc() 2: 3: var db = new NorthwindDataContext(); 4: foreach (var product in db.Ten_Most_Expensive_Products() 5: Console.WriteLine(product.TenMostExpensiveProducts+“t“+ product.UnitPrice ); 6: ,02:26:41,28,数据排序、分组,1: static void ObjectQuery3() 2: 3: var db = new NorthwindDataContext(); 4: var results = from c in db.Customers where c.City = “London“ orderby c.ContactName
