1 static void Main(string[] args) 2         { 3             //初始化数据库 4             var customers = new[] {   5                 new { CustomerID = 1, FirstName = "Orlando", LastName = "Gee",   6                       CompanyName = "A Bike Store" },   7                 new { CustomerID = 2, FirstName = "Keith", LastName = "Harris",   8                       CompanyName = "Bike World" },  9                 new { CustomerID = 3, FirstName = "Donna", LastName = "Carreras",  10                       CompanyName = "A Bike Store" },  11                 new { CustomerID = 4, FirstName = "Janet", LastName = "Gates",  12                       CompanyName = "Fitness Hotel" }, 13                 new { CustomerID = 5, FirstName = "Lucy", LastName = "Harrington",   14                       CompanyName = "Grand Industries" }, 15                 new { CustomerID = 6, FirstName = "David", LastName = "Liu",  16                       CompanyName = "Bike World" }, 17                 new { CustomerID = 7, FirstName = "Donald", LastName = "Blanton",  18                       CompanyName = "Grand Industries" }, 19                 new { CustomerID = 8, FirstName = "Jackie", LastName = "Blackwell",  20                       CompanyName = "Fitness Hotel" }, 21                 new { CustomerID = 9, FirstName = "Elsa", LastName = "Leavitt",  22                       CompanyName = "Grand Industries" }, 23                 new { CustomerID = 10, FirstName = "Eric", LastName = "Lang",   24                       CompanyName = "Distant Inn" }  25             };26 27             var addresses = new[] {  28                 new { CompanyName = "A Bike Store", City = "New York", Country = "United States"},  29                 new { CompanyName = "Bike World", City = "Chicago", Country = "United States"}, 30                 new { CompanyName = "Fitness Hotel", City = "Ottawa", Country = "Canada"}, 31                 new { CompanyName = "Grand Industries", City = "London",   32                       Country = "United Kingdom"},  33                 new { CompanyName = "Distant Inn", City = "Tetbury", Country = "United Kingdom"} 34             };35 36             //选中数据库中的FirstName37             IEnumerable<string> customerFirstNames =38     customers.Select(cust => cust.FirstName);39             //将FirstNames显示40             foreach (string name in customerFirstNames)41             {42                 Console.WriteLine(name);43             }44             Console.WriteLine();45 46             //先根据地址的国家找到满足条件的，然后再选中满足条件的公司名字47             IEnumerable<string> usCompanies =48     addresses.Where(addr => String.Equals(addr.Country, "United States"))49              .Select(usComp => usComp.CompanyName);50 51             foreach (string name in usCompanies)52             {53                 Console.WriteLine(name);54             }55             Console.WriteLine();56 57             //先根据公司名字首字母排序，然后再选中公司名字58             IEnumerable<string> companyNames =59     addresses.OrderBy(addr => addr.CompanyName).Select(comp => comp.CompanyName);60 61             foreach (string name in companyNames)62             {63                 Console.WriteLine(name);64             }65             Console.WriteLine();66             67             //按国家分组68             var companiesGroupedByCountry =69     addresses.GroupBy(addrs => addrs.Country);70             //分别显示每个国家的公司数量与其名字71             foreach (var companiesPerCountry in companiesGroupedByCountry)72             {73                 Console.WriteLine("Country: {0}\t{1} companies",74                         companiesPerCountry.Key, companiesPerCountry.Count());75                 foreach (var companies in companiesPerCountry)76                 {77                     Console.WriteLine("\t{0}", companies.CompanyName);78                 }79             }80             Console.WriteLine();81 82             //匹配中间变量CompanyName相等的，从而构造出所需要的输出83             var citiesAndCustomers = customers84                                       .Select(c => new { c.FirstName, c.LastName, c.CompanyName })85                                       .Join(addresses, custs => custs.CompanyName, addrs => addrs.CompanyName,86                                       (custs, addrs) => new { custs.FirstName, custs.LastName, addrs.Country });87 88             foreach (var row in citiesAndCustomers)89             {90                 Console.WriteLine(row);91             }92             Console.WriteLine();93 94             Console.ReadKey();95         }