Linq 基本語法 - Join

Join
The Join operator performs an inner equijoin on two sequences based on keys extracted from each element in the sequences.

public static IEnumerable<V> Join<T, U, K, V>(
this IEnumerable<T> outer,
IEnumerable<U> inner,
Func<T, K> outerKeySelector,
Func<U, K> innerKeySelector,
Func<T, U, V> resultSelector);

在這裡建立了兩個List

List ltUser = new List(20);

for (int i = 0; i < 20; i++)

{

  ltUser.Add(new User(i,"AA"));                

}

List ltUserInfo = new List(10);

for (int i = 0; i < 10; i++)

{

  ltUserInfo.Add(new UserInfo(i,"CC"));                

}

Linq語法如下:

var Users=ltUser.Join(ltUserInfo,

  a=>a.No,

  b=>b.No,

  (a,b)=>new{id=a.No,UserName=a.Name,Department=b.Department});

StringBuilder sb=new StringBuilder();

foreach (var item in Users)

{

  sb.AppendLine(item.ToString());                           

}

richTextBox1.Text=sb.ToString();

最後產生如下結果

最後產生的結果，有點像是Inner Join
其實最近有點懶散，並沒有很仔細去看這本書
今天就先練習到這。