Get rows count based on column value from DataTable using Linq in ASP.Net

Refer below Sample code for your reference and implement in your code as per your code logic.

C#

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!this.IsPostBack)
        {
            DataSet ds = new DataSet();
            DataTable dt = new DataTable("Employee");
            dt.Columns.Add(new DataColumn("Id", typeof(string)));
            dt.Columns.Add(new DataColumn("Empname", typeof(string)));
            dt.Columns.Add(new DataColumn("Des", typeof(string)));
            dt.Rows.Add(1, "sk", "eng");
            dt.Rows.Add(2, "rm", "eng");
            dt.Rows.Add(3, "sk", "dt");
            ds.Tables.Add(dt);

            Array distinctName;
            for (int i = 0; i < ds.Tables.Count; i++)
            {
                distinctName = ds.Tables[i].AsEnumerable()
                               .GroupBy(x => x.Field<string>("Empname"))
                               .Select(g => new
                               {
                                   Name = g.Key,
                                   Count = g.Select(x => x.Field<string>("Empname")).Count()
                               }).ToArray();
            }
        }
    }

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Dim ds As DataSet = New DataSet()
        Dim dt As DataTable = New DataTable("Employee")
        dt.Columns.Add(New DataColumn("Id", GetType(String)))
        dt.Columns.Add(New DataColumn("Empname", GetType(String)))
        dt.Columns.Add(New DataColumn("Des", GetType(String)))
        dt.Rows.Add(1, "sk", "eng")
        dt.Rows.Add(2, "rm", "eng")
        dt.Rows.Add(3, "sk", "dt")
        ds.Tables.Add(dt)
        Dim distinctName As Array
        For i As Integer = 0 To ds.Tables.Count - 1
            distinctName = ds.Tables(i).AsEnumerable().GroupBy(Function(x) x.Field(Of String)("Empname")).[Select](Function(g) New With {Key .Name = g.Key, Key .Count = g.[Select](Function(x) x.Field(Of String)("Empname")).Count()}).ToArray()
        Next
    End If
End Sub

Screenshot