Insert all row from DataGridView to database using C# in Windows Forms Application

Hi! I used this code:

object filename = @"F:\Test.docx";
Microsoft.Office.Interop.Word.Application app = new Microsoft.Office.Interop.Word.Application();
Microsoft.Office.Interop.Word.Document doc = new Microsoft.Office.Interop.Word.Document();
object readOnly = false;
object isVisible = true;
object missing = System.Reflection.Missing.Value;
doc = app.Documents.Open(ref filename, ref missing, ref readOnly, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref isVisible);
List<string> data = new List<string>();
for (int i = 0; i < doc.Paragraphs.Count; i++)
{
    string temp = doc.Paragraphs[i + 1].Range.Text.Trim();
    if (temp != string.Empty)
    {
        data.Add(temp);
    }
}
 
DataTable dt = new DataTable();
dt.Columns.AddRange(new DataColumn[3] { new DataColumn("Id", typeof(int)), new DataColumn("Character"), new DataColumn("Number", typeof(int)) });
for (int i = 0; i < data.Count; i++)
{
  
    string txt = data[i].ToUpper();
    char chr = txt[0];
    int number = (int)chr;
    int value = 0;
    if (number > 1039)
    {
        value = (number + 1) - 1040;
    }
    else
    {
        value = (number + 1) - 65;
    }
    dt.Rows.Add((i + 1), txt , value);
}
gvDetails.DataSource = dt;
gvDetails.DataBind();
doc.Close(ref missing, ref missing, ref missing);

it’s worked. I want insert result from datagridview into database.

If separate exists then update else insert.

private void Form1_Load(object sender, EventArgs e)
        {
            this.BindDataGridView();
        }

        private void BindDataGridView()
        {            
            dt.Columns.AddRange(new DataColumn[3] { new DataColumn("Id", typeof(int)), new DataColumn("Separate"), new DataColumn("Number", typeof(int)) });
            this.gvDetails.DataSource = dt;
        }

        private void btnInsert_Click(object sender, EventArgs e)
        {
            foreach (DataGridViewRow row in gvDetails.Rows)
            {
                string constring = @"Data Source=USER-PC;Initial Catalog=dbsUchProc;Integrated Security=true";
                using (SqlConnection con = new SqlConnection(constring))
                {
                    using (SqlCommand cmd = con.CreateCommand())
                    {                        
                        cmd.CommandType = System.Data.CommandType.StoredProcedure;
                        cmd.CommandText = "insertkey";
                        cmd.Parameters.AddWithValue("@Id", row.Cells["Id"].Value);
                        cmd.Parameters.AddWithValue("@Separate ", row.Cells["Separate"].Value);
                        cmd.Parameters.AddWithValue("@Number ", row.Cells["Number"].Value);
                        con.Open();
                        cmd.ExecuteNonQuery();
                        con.Close();
                    }
                }
            }
            MessageBox.Show("Records inserted.");
            dt.Clear();
        }

Proc

create procedure insertkey
    @Id char(4),
    @Separate char(24),
    @Number char(1),
as
begin
    if exists(select Separate from tblOtv where Separate = @Separate)
    begin
        update tblOtv
        set Id = @Id,
            Separate = @Separate,
            Number = @Number
        where Separate = @Separate
    end
    else
    begin
        insert into tblOtv(Id, Separate,Number)values(@Id, @Separate,@Number)    
    end
end

I used this script but not insert data into database. It’s only add one row into database. Can you help me?