如何使用LINQ查询表达式

Question

组数据表的结果，我有以下的DataTable

DataTable BookTable = new DataTable(); 
//Add columns in Book Table 
BookTable.Columns.Add("BookCategory", typeof(string)); 
BookTable.Columns.Add("BookName", typeof(string)); 
//Add rows in Book Table 
BookTable.Rows.Add("Programming", "C# basics"); 
BookTable.Rows.Add("Programming", "Java basics"); 
BookTable.Rows.Add("Networking", "Networking Basics"); 
BookTable.Rows.Add("Database", "Intro to Database"); 

我想筛选出书类别列的基础这对图书名字，我写了下面的Lambda表达式

var BooksList = from Book in BookTable.AsEnumerable() 
       group Book by Book.Field<string>("BookCategory") into g 
       let list = g.ToList() 
       select new 
       { 
        BookCategory = g.Key, 

        BookNames = list.Select(x => x.Field<string>("BookName").ToString())     }; 

现在我必须按以下格式打印出来;

1. 编程
   • C＃基础
   • Java基础
2. 网络
   • 网络基础
3. 数据库
   • 简介数据库

我想知道我怎么可以从下面的代码书分类买到这本书的名称;

foreach(var Book in BooksList) 
{ 
    Console.WriteLine(Book.BookCategory); 
    //logic to Obtain Book Names Here ; 
} 

Answer 1

你需要在你的代码中插入的string.join：

var BooksList = from Book in BookTable.AsEnumerable() 
         group Book by Book.Field<string>("BookCategory") into g 
         let list = g.ToList() 
         select new 
         { 
          BookCategory = g.Key, 

          BookNames = string.Join(" ; ",list.Select(x => x.Field<string>("BookName").ToString())) 
         };