搜索列表中的.Net 3.5，其analagous到SQL - 中（值1，值2，...，值N）列

Question

我有List<ColumnDiff> columnDiffList

的

public class ColumnDiff 
    { 
     public string columnName; 
     public string leftValue; 
     public string rightValue; 
    } 

我需要確定是否有是columnName爲「A」，「B」，「C」的元素。提取子列表並不是必需的。

在SQL方面
columName在（ 'A'， 'B'， 'C'）

如何代碼，在LINQ

Answer 1

有幾種方法，這裏是一個簡單的例子：

namespace ConsoleApplication1 
{ 
    class Program 
    { 
     static void Main(string[] args) 
     { 
      List<ColumnDiff> columnDiffs = new List<ColumnDiff>(); 
      columnDiffs.AddRange(new[] { 
              new ColumnDiff(){columnName="Aa"} 
              ,new ColumnDiff(){columnName="A"} 
              ,new ColumnDiff(){columnName="B"} 
              ,new ColumnDiff(){columnName="Bb"} 
              ,new ColumnDiff(){columnName="C"} 
              ,new ColumnDiff(){columnName="Cc"} 
             }); 

      bool hasItems = columnDiffs.Exists(x => x.columnName == "A" || x.columnName == "B" || x.columnName == "C"); 
      hasItems = columnDiffs.Any(x => x.columnName == "A" || x.columnName == "B" || x.columnName == "C"); 
      hasItems = columnDiffs.FirstOrDefault(x => x.columnName == "A" || x.columnName == "B" || x.columnName == "C") != null; 

      Console.ReadKey(); 
     } 
    } 

    public class ColumnDiff 
    { 
     public string columnName; 
     public string leftValue; 
     public string rightValue; 
    } 
} 

Answer 2

也許這就是你需要：

var searchList = new[] {"A", "B", "C"}; 
var result = columnDiffList.Where(i => searchList.Any(j => j == i.columnName)); 

因此，首先定義要搜索的事物列表，然後使用它對列表（columnDiffList）進行搜索。

Answer 3

var res = from c in columnDiffList where c.columnName == "A" || c.columnName == "B" select c;