Merge duplicate DataTable Rows as comma separated based on Column values using C# and VB.Net in ASP.Net

Hi rajeshg12,

Check this sample. now take its reference.

HTML

<asp:GridView runat="server" ID="gvDetails" />

Namespaces

C#

using System.Data;

VB.Net

Imports System.Data

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    DataTable dt = new DataTable();
    dt.Columns.AddRange(new DataColumn[] { 
                        new DataColumn("Column1"),
                        new DataColumn("Column2"),
                        new DataColumn("Column3"),
                        new DataColumn("Column4") });
    dt.Rows.Add("Nephrology", "2010", "1,3", "SDTM specs,Table prog/QC");
    dt.Rows.Add("Nephrology", "2010", "2,ISE", "ADaM specs,SDTM prog/QC");
    dt.Rows.Add("Nephrology1", "2011", "2,ISE", "ADaM specs,SDTM prog/QC");

    DataTable dtRsult = dt.Clone();
    var distinctRows = dt.DefaultView.ToTable(true, "Column1").Rows.OfType<DataRow>().Select(k => k[0] + "").ToArray();
    foreach (string name in distinctRows)
    {
        var rows = dt.Select("Column1 = '" + name + "'");
        string column3 = "";
        string column4 = "";
        foreach (DataRow row in rows)
        {
            column3 += row["Column3"] + ",";
            column4 += row["Column4"] + ",";
        }
        column3 = column3.Trim(',');
        column4 = column4.Trim(',');

        dtRsult.Rows.Add(rows[0]["Column1"], rows[0]["Column2"], column3, column4);
        column3 = "";
        column4 = "";
    }

    gvDetails.DataSource = dtRsult;
    gvDetails.DataBind();
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    Dim dt As DataTable = New DataTable()
    dt.Columns.AddRange(New DataColumn() {
                        New DataColumn("Column1"),
                        New DataColumn("Column2"),
                        New DataColumn("Column3"),
                        New DataColumn("Column4")})
    dt.Rows.Add("Nephrology", "2010", "1,3", "SDTM specs,Table prog/QC")
    dt.Rows.Add("Nephrology", "2010", "2,ISE", "ADaM specs,SDTM prog/QC")
    dt.Rows.Add("Nephrology1", "2011", "2,ISE", "ADaM specs,SDTM prog/QC")

    Dim dtRsult As DataTable = dt.Clone()
    Dim distinctRows = dt.DefaultView.ToTable(True, "Column1").Rows.OfType(Of DataRow)().Select(Function(k) k(0) & "").ToArray()
    For Each name As String In distinctRows
        Dim rows = dt.Select("Column1 = '" & name & "'")
        Dim column3 As String = ""
        Dim column4 As String = ""
        For Each row As DataRow In rows
            column3 += row("Column3") & ","
            column4 += row("Column4") & ","
        Next
        column3 = column3.Trim(","c)
        column4 = column4.Trim(","c)
        dtRsult.Rows.Add(rows(0)("Column1"), rows(0)("Column2"), column3, column4)
        column3 = ""
        column4 = ""
    Next
    gvDetails.DataSource = dtRsult
    gvDetails.DataBind()
End Sub

Screenshot