C#sql查询导出为excel文件，并最终释放excel资源。

public bool ExcelOut(string filename,string sql1,string sql2)
  {

   try
   {
    // Start a new workbook in Excel.
    m_objExcel = new Excel.Application();
    m_objBooks = (Excel.Workbooks)m_objExcel.Workbooks;
    m_objBook = (Excel._Workbook)(m_objBooks.Add(m_objOpt));

    // Create a QueryTable that starts at cell A1.
    m_objSheets = (Excel.Sheets)m_objBook.Worksheets;

    m_objSheet = (Excel._Worksheet)(m_objSheets.get_Item(1));
    m_objRange = m_objSheet.get_Range("A1", m_objOpt);
    m_objQryTables = m_objSheet.QueryTables;
    m_objQryTable = (Excel._QueryTable)m_objQryTables.Add(
     Conn, m_objRange, sql1);
    m_objQryTable.RefreshStyle = Excel.XlCellInsertionMode.xlInsertEntireRows;
    m_objQryTable.Refresh(false);

    m_objSheets = (Excel.Sheets)m_objBook.Worksheets;

    m_objSheet = (Excel._Worksheet)(m_objSheets.get_Item(2));
    m_objRange = m_objSheet.get_Range("A1", m_objOpt);
    m_objQryTables = m_objSheet.QueryTables;
    m_objQryTable = (Excel._QueryTable)m_objQryTables.Add(
     Conn, m_objRange, sql2);
    m_objQryTable.RefreshStyle = Excel.XlCellInsertionMode.xlInsertEntireRows;
    m_objQryTable.Refresh(false);

    // Save the workbook and quit Excel.
    m_objBook.SaveAs(filename, m_objOpt, m_objOpt,
     m_objOpt, m_objOpt, m_objOpt, Excel.XlSaveAsAccessMode.xlNoChange, m_objOpt, m_objOpt,
     m_objOpt, m_objOpt);
    //m_objBook.Close(false, m_objOpt, m_objOpt);
    //m_objExcel.Quit();

    return true;
   }
   catch
   {
    return false;
   }
   finally
   {

    System.Runtime.InteropServices.Marshal.ReleaseComObject((object)m_objQryTable);
    m_objQryTable = null;
    System.Runtime.InteropServices.Marshal.ReleaseComObject((object)m_objQryTables);
    m_objQryTables = null;
    System.Runtime.InteropServices.Marshal.ReleaseComObject((object)m_objRange);
    m_objRange = null;
    System.Runtime.InteropServices.Marshal.ReleaseComObject((object)m_objSheet);
    m_objSheet = null;
    System.Runtime.InteropServices.Marshal.ReleaseComObject((object)m_objSheets);
    m_objSheets = null;
    m_objBook.Close(false,m_objOpt,m_objOpt);
    System.Runtime.InteropServices.Marshal.ReleaseComObject((object)m_objBook);
    m_objBook = null;
    m_objBooks.Close();
    System.Runtime.InteropServices.Marshal.ReleaseComObject((object)m_objBooks);
    m_objBooks = null;
    m_objExcel.Quit();
    System.Runtime.InteropServices.Marshal.ReleaseComObject((object)m_objExcel);
    m_objExcel = null;

    GC.Collect();
    GC.WaitForPendingFinalizers();
   }

  }