Question

我确实有List<ColumnDiff> columnDiffList

的

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

我需要确定是否存在columnName为“A”，“B”，“C”的元素提取子列表并不重要。

在SQL术语中 columName in（'A'，'B'，'C'）

如何在LINQ中编写代码

Answer 1

也许这就是你所需要的：

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

首先定义要搜索的内容列表，然后使用它来对列表进行搜索（columnDiffList）。

Answer 2

有几种方法，这是一个简单的例子：

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 3

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

搜索列表.Net 3.5，类似于SQL - 列（value1，value2，...，value）

3 个答案: