C#

i have many payment rows in same date and i want to count how many payments i this date and put count result in new 1 row

i'm made it manually by excel but i want make it in c# with SQL Server & Data Grid View

this 2 photos make you understand
https://i.stack.imgur.com/mWj1M.png
https://i.stack.imgur.com/UhOzB.png

public class Person
        {
            public Person()
            {
                Children = new ObservableCollection<Person>();
            }
            public string Name { get; set; }
            public int Age { get; set; }
            public ObservableCollection<Person> Children { get; set; }
        }
ObservableCollection<Person> Souce = new ObservableCollection<Person>();
            Person P1 =
            new Person()
            {
                Name = "GrandFather",
                Age = 90
            };
            Person P11 = new Person()
            {
                Name = "Father1",
                Age = 60
            };
            Person P111 = new Person()
            {
                Name = "Child1",
                Age = 30
            };
            P11.Children.Add(P111);
            Person P12 = new Person()
            {
                Name = "Father2",
                Age = 60
            };

            P1.Children.Add(P11);
            P1.Children.Add(P12);

            Person P2 =
            new Person()
            {
                Name = "GrandFather2",
                Age = 91
            };
            Person P3 =
            new Person()
            {
                Name = "GrandFather3",
                Age = 92
            };
            Souce.Add(P1);
            Souce.Add(P2);
            Souce.Add(P3);
            trVwPerson.ItemsSource = Souce;

<TreeView Name="trVwPerson" xmlns:obj="clr-namespace:TestWpf">
  <TreeView.ItemTemplate>
     <HierarchicalDataTemplate DataType = "{x:Type obj:Person}" ItemsSource="{Binding Path=Children}">
         <StackPanel Orientation="Horizontal">
             <TextBlock Text="{Binding Path=Name}"/>
             <TextBlock Width="10"/>
             <TextBlock Text="{Binding Path=Age}"/>
         </StackPanel>
      </HierarchicalDataTemplate>
   </TreeView.ItemTemplate>
</TreeView>

public partial class Form1 : Form
    {        
        public Form1()
        {
            InitializeComponent();
            //progressBar1.Visible = false;
            progressBar1.Minimum = 0;
            progressBar1.Maximum = 100;

            this.Paint += new System.Windows.Forms.PaintEventHandler(this.Form1_Paint);

        }
        int iNum = 0;        
        private void btnDrawText_Click(object sender, EventArgs e) //PaintEventArgs e
        {            
            progressBar1.Value = 0;
            progressBar1.Visible = true;
            this.timer1.Interval = 100;
            this.timer1.Enabled = true;            

        }
        private void ShadowedTextPaint(PaintEventArgs e, int num)
        {
            using (Font font1 = new Font("Times New Roman", 250, FontStyle.Bold, GraphicsUnit.Pixel))
            {
                PointF pointF1 = new PointF(310, 270);
                e.Graphics.DrawString(num.ToString(), font1, Brushes.LightGreen, pointF1);                
                lblNum.Text = num.ToString();
            }            

        }
        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            ShadowedTextPaint(e, iNum);
        }
        private void timer1_Tick(object sender, EventArgs e)
        {            
            if (progressBar1.Value < 100)
            {                
                Random rd = new Random();
                iNum = rd.Next(0, 999);                
                progressBar1.Value++;
            }
            else
            {                
                this.timer1.Enabled = false;
                progressBar1.Visible = false;                
            }

        }
  }

public DirectoryEntry FindEntry(ADUserId id)
{
    if (id == null || !id.IsValid)
        return null;
    using (var search = new DirectorySearcher(RootEntry))
    {
        if (!string.IsNullOrEmpty(id.SAMAccountName))
        {
            search.Filter = $"(&(objectCategory=person)(objectClass=user)(SAMAccountName={id.SAMAccountName}))";
        }
        else if (!string.IsNullOrEmpty(id.InteractName))
        {
            search.Filter = $"(&(objectCategory=person)(objectClass=user)(interactUsername={id.InteractName}))";
        }
        else
        {
            return null;
        }

        var result = search.FindOne();
        var e = result?.GetDirectoryEntry();
        if (e != null)
        {
            id.SAMAccountName = GetProperty(e, "SAMAccountName") as string;
            id.InteractName = GetProperty(e, "interactUsername") as string;
        }
        return e;
    }
}

public DirectoryEntry FindEntry(string interactName)
{
    if (interactName == null)
        return null;
    using (var search = new DirectorySearcher(RootEntry))
    {
        search.Filter = $"(&(objectCategory=person)(objectClass=user)(interactUsername={interactName}))";
        var result = search.FindOne();
        return result?.GetDirectoryEntry();
    }
}