How to search on two text boxes from a database and display on gridview

If I was doing this then I'd have some code like this:

protected void Search_Click(object sender, EventArgs e)
  {

      var constr = ConfigurationManager.ConnectionStrings["ConnectToDB"].ConnectionString;

      var sql = new StringBuilder();
      sql.Append("Select [ITEM No#], [Company Name], [Discipline Required], [Service Description], Institution, [Award Date]");
      sql.Append(" from PSP_Report ");

      using (var con = new SqlConnection(constr))
      {
          using (var xp = new SqlCommand())
          {
              xp.Connection = con;

              var andRequired = false;
              var whereAdded = false;

              AddASearchItem(ref whereAdded, ref andRequired, sql, Search1.Text, "[ITEM NO#]", 1, xp);
              AddASearchItem(ref whereAdded, ref andRequired, sql, Search2.Text, "[Company Name]", 2, xp);
              AddASearchItem(ref whereAdded, ref andRequired, sql, Search3.Text, "[Discipline Required]", 3, xp);

              xp.CommandText = sql.ToString();

              con.Open();

              var da = new SqlDataAdapter {SelectCommand = xp};

              var ds = new DataSet();
              da.Fill(ds);
              GridView1.DataSource = ds.Tables[0];
              GridView1.DataBind();
              con.Close();
          }
      }
  }

  protected void AddASearchItem(ref bool whereAdded, ref bool andRequired, StringBuilder s,
      string searchText, string colName, int item, SqlCommand cmd)
  {
      //Add a search item to the string builder determining whether or not the words 'WHERE' or 'AND'
      //need to be added. Add an appropriate parameter to the sql command.
      if (string.IsNullOrEmpty(searchText)) return;
      if (!whereAdded)
      {
          s.Append(" where ");
          whereAdded = true;
      }
      else
          if (andRequired) s.Append(" AND");
      s.Append(string.Format("  {0} LIKE @search{1}", colName,item));
      cmd.Parameters.AddWithValue("@search" + item.ToString(), "%" + searchText + "%");
      andRequired = true;
  }

Points to note:
1 - I've used a StringBuilder to dynamically build up the sql command text. This is better than concatenating strings (because strings are immutable)
2 - I have a little function that only adds search items onto the SQL if the relevent search textbox has something in it.
3 - I need to work out if the words " WHERE " or " AND " need to be added to the SQL.
4 - If none of the search boxes have anything in them then all records will be returned