How do i write a method for this code

Question

 
Dear friends how do i write a method for the code marked in red as it is repeating. I want to write a method and call it in place of the code given in red.. Can u`ll plzzz help
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  string menuType;
  GblDefinition obj = new GblDefinition();
  protected void Page_Load(object sender, EventArgs e)
  {
  menuType = Request.QueryString["type"];
  if (!Page.IsPostBack)
  {
  if (menuType == "city")
  {
  lbltitle.Text = "City Details";
 
  BoundField field = new BoundField();
  field.DataField = "cityid";
  field.HeaderText = "City ID";
  DataControlField col = field;
  GVDetails.Columns.Add(col);

  field = new BoundField();
  field.DataField = "cityname";
  field.HeaderText = "City";
  col = field;
  GVDetails.Columns.Add(col);

  DataSet ds1 = obj.LoadDataSet("Select * from city_master");
  GVDetails.DataSource = ds1.Tables[0];
  GVDetails.DataBind();

 
 
  }
  else if (menuType == "state")
  {
   lbltitle.Text = "State Details";
  BoundField field = new BoundField();
  field.DataField = "stateid";
  field.HeaderText = "State ID";
  DataControlField col = field;
  GVDetails.Columns.Add(col);

  field = new BoundField();
  field.DataField = "statename";
  field.HeaderText = "State";
  col = field;
  GVDetails.Columns.Add(col);


  DataSet ds2 = obj.LoadDataSet("select * from state_master");
  GVDetails.DataSource=ds2.Tables[0];
  GVDetails.DataBind();
  }
  else if(menuType=="country")
  {
  lbltitle.Text = "Country Details";
  BoundField field = new BoundField();
  field.HeaderText = "Country ID";
  field.DataField = "countryid";
  DataControlField col = field;
  GVDetails.Columns.Add(col);

  field = new BoundField();
  field.DataField = "countryname";
  field.HeaderText = "Country";
  col = field;
  GVDetails.Columns.Add(col);

  DataSet ds3 = obj.LoadDataSet("select * from country_master");
  GVDetails.DataSource=ds3.Tables[0];
  GVDetails.DataBind();
  }
  else if(menuType=="category")
  {
  lbltitle.Text = "Category Details";
  BoundField field = new BoundField();
  field.HeaderText = "Category ID";
  field.DataField = "categoryid";
  DataControlField col = field;
  GVDetails.Columns.Add(col);

  field = new BoundField();
  field.DataField = "categoryname";
  field.HeaderText = "Category";
  col = field;
  GVDetails.Columns.Add(col);

  DataSet ds4 = obj.LoadDataSet("select * from category_master");
  GVDetails.DataSource=ds4.Tables[0];
  GVDetails.DataBind();
  }
  else if(menuType=="designation")
  {
  lbltitle.Text = "Desination Details";
  BoundField field = new BoundField();
  field.HeaderText = "Designation ID";
  field.DataField = "designationid";
  DataControlField col = field;
  GVDetails.Columns.Add(col);

  field = new BoundField();
  field.HeaderText = "Designation";
  field.DataField = "designation";
  col = field;
  GVDetails.Columns.Add(col);

  DataSet ds5 = obj.LoadDataSet("select * from designation_master");
  GVDetails.DataSource=ds5.Tables[0];
  GVDetails.DataBind();
  }
  }
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