title: How can add multiple data without add same data?
body: <p>How can add multiple data without add same data?
  I am tried to correct it.</p>
  
  <pre><code>public partial class SalaryCalculator : Form
  {
  
      public SalaryCalculator()
      {
          InitializeComponent();
      }
  
  
      public Double basicAmount, houseRent, medicalAllowance, totalHouseRent, totalMedicalAllowance, totalSalary;
      public int id = 0;
  
      private void addButton_Click(object sender, EventArgs e)
      {
  
          ListViewItem newList = new ListViewItem((++id).ToString());
  
  
          string employeeName = nameTextBox.Text;
  
          double basicAmount = Convert.ToDouble(basicTextBox.Text);
          double houseRent = Convert.ToDouble(houseRentTextBox.Text);
          double medicalAllowance = Convert.ToDouble(medicalTextBox.Text);
  
  
          totalHouseRent = (basicAmount*houseRent)/100;
          totalMedicalAllowance = (basicAmount*medicalAllowance)/100;
          totalSalary = basicAmount + totalHouseRent + totalMedicalAllowance;
          totalTextBox.Text = totalSalary.ToString();
  
  
          newList.SubItems.Add(employeeName);
          newList.SubItems.Add(totalSalary.ToString());
          listView1.Items.Add(newList);
  
  
  
          }
  
      }
  }
  </code></pre>
  
  <p><strong>How can add multiple data without add same data?</strong></p>