//左外联接
public static void LeftOutJoinRun()
{
var racers = from r in Formulal.GetChampions()
from y in r.Years
select new
{
Year = y,
Name = r.FirstName + " " + r.LastName
};
var teams = from t in Formulal.GetContructorChampions()
from y in t.Years
select new
{
Year = y,
Name = t.Name
};
var racersAndTeams = (from r in racers
join t in teams on r.Year equals t.Year into rt
from t in rt.DefaultIfEmpty()
orderby r.Year
select new
{
r.Year,
Champion = r.Name,
Constructor = t == null ? "no constructor" : t.Name
}).Take(10);
Console.WriteLine("输出结果：");
foreach (var item in racersAndTeams)
{
Console.WriteLine($"{item.Year}:{item.Champion,-10} {item.Constructor}");
}
}
//内连接
public static void InnerJoinRun()
{
var racers = from r in Formulal.GetChampions()
from y in r.Years
select new
{
Year = y,
Name = r.FirstName + " " + r.LastName
};
var teams = from t in Formulal.GetContructorChampions()
from y in t.Years
select new
{
Year = y,
Name = t.Name
};
var racersAndTeams = (from r in racers
join t in teams on r.Year equals t.Year
orderby t.Year
select new
{
r.Year,
Champion = r.Name,
Constructor = t.Name
}).Take(10);
Console.WriteLine("输出结果：");
foreach (var item in racersAndTeams)
{
Console.WriteLine($"{item.Year}:{item.Champion,-20} {item.Constructor}");
}
Console.WriteLine();
Console.WriteLine(" 将上述合并为一个LINQ查询:");
var racersAndTeams2 =
(from r in from r1 in Formulal.GetChampions()
from yr in r1.Years
select new
{
Year = yr,
Name = r1.FirstName + " " + r1.LastName
}
join t in
from t1 in Formulal.GetContructorChampions()
from yt in t1.Years
select new
{
Year = yt,
Name = t1.Name
}
on r.Year equals t.Year
orderby t.Year
select new
{
Year = r.Year,
Champion = r.Name,
Constructor = t.Name
}).Take(10);
Console.WriteLine("输出结果：");
foreach (var item in racersAndTeams2)
{
Console.WriteLine($"{item.Year}:{item.Champion,-20} {item.Constructor}");
}
}