title: Error When Add new DataColumn in DataTable?
body: <p>how to add new column in new DataTable But Erorr</p>
  
  <pre><code>private void LoadtoList()
  {
      SqlDataAdapter sa = new SqlDataAdapter("SELECT * FROM EmpSign", _constr);
      dt = new DataTable("CCTVTable");
      sa.Fill(dt);
  
      dtpass = new DataTable("CCTVpassword");
      SqlDataAdapter sa2 = new SqlDataAdapter("SELECT PASSWORD FROM Emp e WHERE e.EmpID IN ('f2123', 'f2124', 'f2126', 'rt015', 'f2133')",
          ConfigurationManager.ConnectionStrings["SaraburiEmp"].ConnectionString);
      sa2.Fill(dtpass);
      DataColumn dc = new DataColumn();
      dc = dtpass.Columns["password"];
      dt.Columns.Add(dc);
  }
  </code></pre>
  
  <hr>
  
  <blockquote>
    <p>Column 'PASSWORD' already belongs to
    another DataTable.  Description: An
    unhandled exception occurred during
    the execution of the current web
    request. Please review the stack trace
    for more information about the error
    and where it originated in the code. </p>
    
    <p>Exception Details:
    System.ArgumentException: Column
    'PASSWORD' already belongs to another
    DataTable.</p>
    
    <p>Source Error: </p>
  </blockquote>
  
  <pre><code>Line 1040:        DataColumn dc = new DataColumn();
  Line 1041:        dc = dtpass.Columns["password"];
  Line 1042:        dt.Columns.Add(dc);
  Line 1043:    }
  Line 1044:}
  </code></pre>