ASP.Net: Concatenate multiple rows into single in LINQ using C#

Hi sureshMGR,

Refer below example.

Database

For this example I have used of Northwind database that you can download using the link given below.

Download Northwind Database

Namespaces

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

Code

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        this.BindGrid();
    }
}
private void BindGrid()
{
    using (NORTHWINDEntities entities = new NORTHWINDEntities())
    {
        var result = (from category in entities.Categories
                        join product in entities.Products on category.CategoryID equals product.CategoryID
                        select new { category.CategoryID, category.CategoryName, product.ProductName }).ToList();

        DataTable dt = new DataTable();
        dt.Columns.AddRange(new DataColumn[3] { new DataColumn("CategoryID"), 
                                                new DataColumn("CategoryName"), 
                                                new DataColumn("Products") });

        List<int> catIds = result.Select(x => x.CategoryID).Distinct().ToList();
        foreach (int id in catIds)
        {
            var data = result.Where(x => x.CategoryID == id);
            string products = string.Join(",", result.Where(x => x.CategoryID == id).Select(x => x.ProductName).ToList());
            dt.Rows.Add(id, data.Select(x => x.CategoryName).FirstOrDefault(), products);
        }
    }
}

Screenshot