how to Compair two different dataset of same column in c#

The error you're encountering ("Specified cast is not valid") occurs when there is a problem with the data type conversion. It's possible that the values in the "Emp_no" column of your DataEmp dataset are not valid integers. Try this

string id = row["ID"].ToString(); // Convert to string
if (DataEmp.Tables[0].AsEnumerable().Any(dataRow => dataRow.Field("Emp_no") == id))

int id = Convert.ToInt32(row["ID"]); // Assuming "ID" is the column name in ExcelData if (DataEmp.Tables[0].AsEnumerable().Any(dataRow => dataRow.Field("Emp_no") == id))                                                               showing error in Specified cast is not valid.

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        // Sample data1 and data2 datasets
        List data1 = new List
        {
            new Data { ID = 1 },
            new Data { ID = 5 },
            // ... (add more data)
        };

        List data2 = new List
        {
            new Data { ID = 3 },
            new Data { ID = 5 },
            // ... (add more data)
        };

        // Check IDs in data1 against data2 and separate them into lists
        List list1 = new List();
        List list2 = new List();

        foreach (var item in data1)
        {
            if (data2.Any(d => d.ID == item.ID))
            {
                list1.Add(item.ID);
            }
            else
            {
                list2.Add(item.ID);
            }
        }

        Console.WriteLine("IDs present in both datasets (list1):");
        foreach (var id in list1)
        {
            Console.WriteLine(id);
        }

        Console.WriteLine("IDs not found in second dataset (list2):");
        foreach (var id in list2)
        {
            Console.WriteLine(id);
        }
    }
}

class Data
{
    public int ID { get; set; }
}

i am using this two dataset to compair Id column .

1) DataSet ExcelData = new DataSet();

dataAdapter.Fill(ExcelData);

2) string Qry = @"SELECT Emp_no FROM EmployeeTable";
   DataSet DataEmp = InProc.RetriveDataSet(Qry);

First ExcelData have 100 record and second DataEmp 500 record. I want to compair first datset to second datset if first dataset value present in second datset that value put in list and if data not present in scond datset put in second list. 

using System;
using System.Collections.Generic;
using System.Linq;

namespace DatasetComparison
{
    class Program
    {
        static void Main(string[] args)
        {
            // Sample data
            List data1 = new List
            {
                new Data { ID = 1, Name = "Item 1" },
                new Data { ID = 2, Name = "Item 2" },
                // ...
            };

            List data2 = new List
            {
                new Data { ID = 1, Name = "Item 1" },
                new Data { ID = 3, Name = "Item 3" },
                // ...
            };

            // Find IDs present in data1 that are also present in data2
            List list1 = data1.Where(d1 => data2.Any(d2 => d2.ID == d1.ID)).Select(d1 => d1.ID).ToList();

            // Find IDs present in data1 that are not present in data2
            List list2 = data1.Where(d1 => !data2.Any(d2 => d2.ID == d1.ID)).Select(d1 => d1.ID).ToList();

            // Display the results
            Console.WriteLine("IDs present in both data1 and data2:");
            foreach (int id in list1)
            {
                Console.WriteLine(id);
            }

            Console.WriteLine("IDs present in data1 but not in data2:");
            foreach (int id in list2)
            {
                Console.WriteLine(id);
            }
        }
    }

    class Data
    {
        public int ID { get; set; }
        public string Name { get; set; }
        // Other properties of your data item
    }
}

try sample logic:

 List data1 = new List { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
        List data2 = new List { 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50 };

        List list1 = new List();
        List list2 = new List();

        foreach (int id in data1)
        {
            if (data2.Contains(id))
            {
                list1.Add(id);
            }
            else
            {
                list2.Add(id);
            }
        }

        Console.WriteLine("IDs present in data2:");
        foreach (int id in list1)
        {
            Console.WriteLine(id);
        }

        Console.WriteLine("IDs not found in data2:");
        foreach (int id in list2)
        {
            Console.WriteLine(id);
        }