先建一個實體類
class Customer
{
public String ID { get; set; }
public String Name { get; set; }
public String Country { get; set; }
public String Price { get; set; }
public override string ToString()
{
return "ID = "+ID+",Name = "+Name+",Country = "+Country+",Price = "+Price;
}
}
對這個實體類進行相應的查詢
List<Customer> lists = new List<Customer>
{
new Customer
{ID ="0001",
Name = "computer",
Country = "korea",
Price = 111},
new Customer
{ID ="0002",
Name = "phone",
Country = "japan",
Price = 111},
new Customer
{ID ="0003",
Name = "pad",
Country = "usa",
Price = 111},
new Customer
{ID ="0004",
Name = "map3",
Country = "china",
Price = 111},
new Customer
{ID ="0005",
Name = "fuduji",
Country = "china",
Price = 111},
};
var item = from n in lists
where n.Country == "china"
select n;
foreach (Customer i in item)
{
Console.WriteLine(i);
}
var item = from n in lists
where n.Country == "china"
select n.Name;//改成select n.Name+"er"; 在查詢出的數據后面加一個尾巴再輸出
foreach (String i in item)
{
Console.WriteLine(i);
}
Console.ReadKey();
---------------------------------------------------------
后面的查詢部分還可以改成這樣
var item = from n in lists
where n.Country == "china"
select new { n.Name,n.Country };//在select語句中映射多個屬性只能用這種創先新對象的方式
foreach (var i in item)
{
Console.WriteLine(i);
}
//另外還有一種相類似的方法，應該說這才是真正的在select語句里面創建新的方法，這種方法常用在先給要查詢的實體類實例化，然后再從中查詢需要的內容（干巴巴的我也講不太清楚，看看代碼）
先創建一個實體類是用來提供數據的
class Com
{
public String A { get; set; }
public String B { get; set; }
public String C { get; set; }
public String D { get; set; }
}
再創建一個實體類（就是上個例子用到的那個類）
class Customer
{
public String ID { get; set; }
public String Name { get; set; }
public String Country { get; set; }
public String Price { get; set; }
public override string ToString()
{
return "ID = "+ID+",Name = "+Name+",Country = "+Country+",Price = "+Price;
}
}
接下來是具體的使用了
List<Com> lists = new List<Com>
{
new Com
{
A = "111",
B = "222",
C = "333",
D = "444"
},
new Com
{
A = "aaa",
B = "bbb",
C = "ccc",
D = "ddd"
},
new Com
{
A = "AAA",
B = "BBB",
C = "CCC",
D = "DDD"
}
};
var item = from n in lists
select new Customer
{
ID = n.A,
Name = n.B,
Country = n.C,
Price = n.D
};
foreach(var i in item)
{
Console.WriteLine(i);
}
Console.ReadKey();
}
這種做法在解析數據會時常用到，有時間再回過頭來看看