首先添加数据集合
1 [Serializable]
2 public class Racer : IComparable<Racer>, IFormattable
3 {
4 public Racer()
5 { }
6 public Racer(string firstName, string lastName, string country, int starts, int wins)
7 : this(firstName, lastName, country, starts, wins, null, null)
8 {
9 }
10 public Racer(string firstName, string lastName, string country, int starts, int wins, IEnumerable<int> years, IEnumerable<string> cars)
11 {
12 this.FirstName = firstName;
13 this.LastName = lastName;
14 this.Country = country;
15 this.Starts = starts;
16 this.Wins = wins;
17 this.Years = new List<int>(years);
18 this.Cars = new List<string>(cars);
19 }
20 public string FirstName { get; set; }
21 public string LastName { get; set; }
22 public string Country { get; set; }
23 public int Wins { get; set; }
24 public int Starts { get; set; }
25 public IEnumerable<string> Cars { get; private set; }
26 public IEnumerable<int> Years { get; private set; }
27
28 public override string ToString()
29 {
30 return String.Format("{0} {1}", FirstName, LastName);
31 }
32
33 public int CompareTo(Racer other)
34 {
35 if (other == null) return -1;
36 return string.Compare(this.LastName, other.LastName);
37 }
38
39 public string ToString(string format)
40 {
41 return ToString(format, null);
42 }
43
44 public string ToString(string format,
45 IFormatProvider formatProvider)
46 {
47 switch (format)
48 {
49 case null:
50 case "N":
51 return ToString();
52 case "F":
53 return FirstName;
54 case "L":
55 return LastName;
56 case "C":
57 return Country;
58 case "S":
59 return Starts.ToString();
60 case "W":
61 return Wins.ToString();
62 case "A":
63 return String.Format("{0} {1}, {2}; starts: {3}, wins: {4}",
64 FirstName, LastName, Country, Starts, Wins);
65 default:
66 throw new FormatException(String.Format("Format {0} not supported", format));
67 }
68 }
69 }
1 private static List<Racer> racers;
2
3 public static IList<Racer> GetChampions()
4 {
5 if (racers == null)
6 {
7 racers = new List<Racer>(40);
8 racers.Add(new Racer("Nino", "Farina", "Italy", 33, 5, new int[] { 1950 }, new string[] { "Alfa Romeo" }));
9 racers.Add(new Racer("Alberto", "Ascari", "Italy", 32, 10, new int[] { 1952, 1953 }, new string[] { "Ferrari" }));
10 racers.Add(new Racer("Juan Manuel", "Fangio", "Argentina", 51, 24, new int[] { 1951, 1954, 1955, 1956, 1957 }, new string[] { "Alfa Romeo", "Maserati", "Mercedes", "Ferrari" }));
11 racers.Add(new Racer("Mike", "Hawthorn", "UK", 45, 3, new int[] { 1958 }, new string[] { "Ferrari" }));
12 racers.Add(new Racer("Phil", "Hill", "USA", 48, 3, new int[] { 1961 }, new string[] { "Ferrari" }));
13 racers.Add(new Racer("John", "Surtees", "UK", 111, 6, new int[] { 1964 }, new string[] { "Ferrari" }));
14 racers.Add(new Racer("Jim", "Clark", "UK", 72, 25, new int[] { 1963, 1965 }, new string[] { "Lotus" }));
15 racers.Add(new Racer("Jack", "Brabham", "Australia", 125, 14, new int[] { 1959, 1960, 1966 }, new string[] { "Cooper", "Brabham" }));
16 racers.Add(new Racer("Denny", "Hulme", "New Zealand", 112, 8, new int[] { 1967 }, new string[] { "Brabham" }));
17 racers.Add(new Racer("Graham", "Hill", "UK", 176, 14, new int[] { 1962, 1968 }, new string[] { "BRM", "Lotus" }));
18 racers.Add(new Racer("Jochen", "Rindt", "Austria", 60, 6, new int[] { 1970 }, new string[] { "Lotus" }));
19 racers.Add(new Racer("Jackie", "Stewart", "UK", 99, 27, new int[] { 1969, 1971, 1973 }, new string[] { "Matra", "Tyrrell" }));
20 racers.Add(new Racer("Emerson", "Fittipaldi", "Brazil", 143, 14, new int[] { 1972, 1974 }, new string[] { "Lotus", "McLaren" }));
21 racers.Add(new Racer("James", "Hunt", "UK", 91, 10, new int[] { 1976 }, new string[] { "McLaren" }));
22 racers.Add(new Racer("Mario", "Andretti", "USA", 128, 12, new int[] { 1978 }, new string[] { "Lotus" }));
23 racers.Add(new Racer("Jody", "Scheckter", "South Africa", 112, 10, new int[] { 1979 }, new string[] { "Ferrari" }));
24 racers.Add(new Racer("Alan", "Jones", "Australia", 115, 12, new int[] { 1980 }, new string[] { "Williams" }));
25 racers.Add(new Racer("Keke", "Rosberg", "Finland", 114, 5, new int[] { 1982 }, new string[] { "Williams" }));
26 racers.Add(new Racer("Niki", "Lauda", "Austria", 173, 25, new int[] { 1975, 1977, 1984 }, new string[] { "Ferrari", "McLaren" }));
27 racers.Add(new Racer("Nelson", "Piquet", "Brazil", 204, 23, new int[] { 1981, 1983, 1987 }, new string[] { "Brabham", "Williams" }));
28 racers.Add(new Racer("Ayrton", "Senna", "Brazil", 161, 41, new int[] { 1988, 1990, 1991 }, new string[] { "McLaren" }));
29 racers.Add(new Racer("Nigel", "Mansell", "UK", 187, 31, new int[] { 1992 }, new string[] { "Williams" }));
30 racers.Add(new Racer("Alain", "Prost", "France", 197, 51, new int[] { 1985, 1986, 1989, 1993 }, new string[] { "McLaren", "Williams" }));
31 racers.Add(new Racer("Damon", "Hill", "UK", 114, 22, new int[] { 1996 }, new string[] { "Williams" }));
32 racers.Add(new Racer("Jacques", "Villeneuve", "Canada", 165, 11, new int[] { 1997 }, new string[] { "Williams" }));
33 racers.Add(new Racer("Mika", "Hakkinen", "Finland", 160, 20, new int[] { 1998, 1999 }, new string[] { "McLaren" }));
34 racers.Add(new Racer("Michael", "Schumacher", "Germany", 287, 91, new int[] { 1994, 1995, 2000, 2001, 2002, 2003, 2004 }, new string[] { "Benetton", "Ferrari" }));
35 racers.Add(new Racer("Fernando", "Alonso", "Spain", 177, 27, new int[] { 2005, 2006 }, new string[] { "Renault" }));
36 racers.Add(new Racer("Kimi", "R?ikk?nen", "Finland", 148, 17, new int[] { 2007 }, new string[] { "Ferrari" }));
37 racers.Add(new Racer("Lewis", "Hamilton", "UK", 90, 17, new int[] { 2008 }, new string[] { "McLaren" }));
38 racers.Add(new Racer("Jenson", "Button", "UK", 208, 12, new int[] { 2009 }, new string[] { "Brawn GP" }));
39 racers.Add(new Racer("Sebastian", "Vettel", "Germany", 81, 21, new int[] { 2010, 2011 }, new string[] { "Red Bull Racing" }));
40 }
41
42 return racers;
43 }
1、where子句
1 var racers = from r in Formula1.GetChampions() 2 where r.Wins > 15 && (r.Country == "Brazil" || r.Country == "Austria") 3 select r; 4 var item = Formula1.GetChampions().Where(p => p.Wins > 15 && (p.Country == "Brazil" || p.Country == "Austria")).Select(r => r);
2、根据索引筛选
1 var racers = Formula1.GetChampions().
2 Where((r, index) => r.LastName.StartsWith("A") && index % 2 != 0);
3、类型筛选
1 object[] data = { "one", 2, 3, "four", "five", 6 };
2 var query = data.OfType<string>();
4、复合的from子句
1 var ferrariDrivers = from r in Formula1.GetChampions()
2 from c in r.Cars
3 where c == "Ferrari"
4 orderby r.LastName
5 select r.FirstName + " " + r.LastName;
6 var item = Formula1.GetChampions().SelectMany(r => r.Cars, (r, c) => new { Racer = r, Car = c }).
7 Where(r => r.Car == "Ferrari").OrderBy(r => r.Racer.LastName).Select(r => r.Racer.FirstName + "" + r.Racer.LastName);
5、排序
1 var racers = from r in Formula1.GetChampions() 2 where r.Country == "Brazil" 3 orderby r.Wins descending 4 select r; 5 var racers2= from r in Formula1.GetChampions() 6 orderby r.Country,r.LastName,r.FirstName 7 select r; 8 var racers3 = Formula1.GetChampions().OrderBy(r => r.Country).ThenBy(r => r.LastName).ThenBy(r => r.FirstName);
6、分组
1
2 var countries = from r in Formula1.GetChampions()
3 group r by r.Country into g
4 orderby g.Count() descending, g.Key
5 where g.Count() >= 2
6 select new { Country = g.Key, Count = g.Count() };
7
8 var item = Formula1.GetChampions().GroupBy(r => r.Country).OrderByDescending(p => p.Count()).
9 ThenBy(p => p.Key).Where(p => p.Count() >= 2).Select(p => new { Country = p.Key, Count = p.Count() });
10
7、内链接
1 var racers = from r in Formula1.GetChampions()
2 from y in r.Years
3 select new
4 {
5 Year = y,
6 Name = r.FirstName + " " + r.LastName
7 };
8
9 var teams = from t in Formula1.GetContructorChampions()
10 from y in t.Years
11 select new
12 {
13 Year = y,
14 Name = t.Name
15 };
8、左连接
1 var racersAndTeams =
2 (from r in racers
3 join t in teams on r.Year equals t.Year into rt
4 from t in rt.DefaultIfEmpty()
5 orderby r.Year
6 select new
7 {
8 Year = r.Year,
9 Champion = r.Name,
10 Constructor = t == null ? "no constructor championship" : t.Name
11 }).Take(10);
9、zip 合并
1 var racerNames = from r in Formula1.GetChampions()
2 where r.Country == "Italy"
3 orderby r.Wins descending
4 select new
5 {
6 Name = r.FirstName + " " + r.LastName
7 };
8
9 var racerNamesAndStarts = from r in Formula1.GetChampions()
10 where r.Country == "Italy"
11 orderby r.Wins descending
12 select new
13 {
14 LastName = r.LastName,
15 Starts = r.Starts
16 };
17
18
19 var racers = racerNames.Zip(racerNamesAndStarts, (first, second) => first.Name + ", starts: " + second.Starts);
10、聚合函数
1 var query = from r in Formula1.GetChampions()
2 let numberYears = r.Years.Count()
3
4 where numberYears >= 3
5 orderby numberYears descending, r.LastName
6 select new
7 {
8 Name = r.FirstName + " " + r.LastName,
9 TimesChampion = numberYears
10 };
11
12 var countries = (from c in
13 from r in Formula1.GetChampions()
14 group r by r.Country into c
15 select new
16 {
17 Country = c.Key,
18 Wins = (from r1 in c
19 select r1.Wins).Sum()
20 }
21 orderby c.Wins descending, c.Country
22 select c).Take(5);
时间： 2024-08-06 14:07:10