title: How to implement a search method in c# and SQL Server?
body: <p>I want to implement a search method in which the user can select the 
  search type from a combobox and enter search value in textbox.</p>
  
  <p>The search button code is here but when I click on the search button, result datagridview is empty.</p>
  
  <p>What is the problem?</p>
  
  <pre><code> private void button1_Click(object sender, EventArgs e)
   {
       SqlCommand cmd = new SqlCommand();
  
       SqlConnection con = new SqlConnection();
       con.ConnectionString = "Data Source=.;Initial Catalog=MyDatabase;Integrated Security=True";
  
       con.Open();
  
       cmd.Connection = con;
  
       DataSet ds = new DataSet();
  
       SqlDataAdapter da = new SqlDataAdapter();
  
       cmd.CommandText = "select * from person where @parameter1=@parameter";
  
       if (comboBox1.SelectedIndex == 0)
       {
          cmd.Parameters.AddWithValue("@parameter1", "name");
       }
       else
       {
          cmd.Parameters.AddWithValue("@parameter1", "code");
       }
  
       cmd.Parameters.AddWithValue("@parameter",textBox1.Text);
  
       da.SelectCommand = cmd;
       da.Fill(ds);
  
       dataGridView1.DataSource = ds.Tables[0];
       con.Close();
  }
  </code></pre>