columnst.cpp

VC++技术内幕(第四版)的实例

// sqlcols.cpp: implementation of the CColumns class
//
// This is a part of the Microsoft Foundation Classes C++ library.
// Copyright (C) 1992-1993 Microsoft Corporation
// All rights reserved.
//
// This source code is only intended as a supplement to the
// Microsoft Foundation Classes Reference and Microsoft
// QuickHelp and/or WinHelp documentation provided with the library.
// See these sources for detailed information regarding the
// Microsoft Foundation Classes product.


#include "stdafx.h"
#include "columnst.h"

/////////////////////////////////////////////////////////////////////////////
// CColumns implementation

IMPLEMENT_DYNAMIC(CColumns, CRecordset)

CColumns::CColumns(CDatabase* pdb)
    : CRecordset(pdb)
{
    //{{AFX_FIELD_INIT(CColumns)
    m_strQualifier = "";
    m_strOwner = "";
    m_strTableName = "";
    m_strColumnName = "";
    m_nDataType = 0;
    m_strTypeName = "";
    m_lPrecision = 0;
    m_lLength = 0;
    m_nScale = 0;
    m_nRadix = 0;
    m_nFields = 11;
    //}}AFX_FIELD_INIT
    m_strQualifierParam = "";
    m_strOwnerParam = "";
    m_strTableNameParam = "";
    m_strColumnNameParam = "";
}

BOOL CColumns::Open(UINT nOpenType /* = snapshot */,
    LPCSTR lpszSQL /* = NULL */, DWORD dwOptions /* = none */)
{
    // Allocation and opening of database not supported
    if (m_pDatabase == SQL_NULL_HDBC || !m_pDatabase->IsOpen())
      return FALSE;

    // allocate an hstmt (if not one already) for the recordset
    RETCODE nRetCode;
    if (m_hstmt == SQL_NULL_HSTMT)
    {
      AFX_SQL_SYNC(::SQLAllocStmt(m_pDatabase->m_hdbc, &m_hstmt));
      if (!Check(nRetCode))
        AfxThrowDBException(SQL_INVALID_HANDLE, m_pDatabase, SQL_NULL_HSTMT);
    }

    TRY
    {
      // set any options, like timeouts, scrolling options
      OnSetOptions(m_hstmt);

      // call the ODBC catalog function with data member params
      RETCODE nRetCode;
      AFX_SQL_ASYNC(this, ::SQLColumns(m_hstmt,
        (m_strQualifierParam.IsEmpty()? (UCHAR FAR *)NULL: (UCHAR FAR *)(const char*)m_strQualifierParam), SQL_NTS,
        (m_strOwnerParam.IsEmpty()? (UCHAR FAR *)NULL: (UCHAR FAR *)(const char*)m_strOwnerParam), SQL_NTS,
        (m_strTableNameParam.IsEmpty()? (UCHAR FAR *)NULL: (UCHAR FAR *)(const char*)m_strTableNameParam), SQL_NTS,
        NULL, SQL_NTS));
      if (!Check(nRetCode))
      {
        AfxThrowDBException(nRetCode, m_pDatabase, m_hstmt);
      }
      // load first record
      MoveFirst();
    }
    CATCH_ALL(e)
    {
      Close();
      THROW_LAST();
    }
    END_CATCH_ALL
    return TRUE;
}

CString CColumns::GetDefaultConnect()
{
    // this minimal connect string will cause ODBC login dialog to be brought up
    return "ODBC;";
}

CString CColumns::GetDefaultSQL()
{
    // there is no default SQL - a direct ODBC call is made instead
    ASSERT(FALSE);
    return "!";
}

void CColumns::DoFieldExchange(CFieldExchange* pFX)
{
    //{{AFX_FIELD_MAP(CColumns)
    pFX->SetFieldType(CFieldExchange::outputColumn);
    RFX_Text(pFX, "table_qualifier", m_strQualifier);
    RFX_Text(pFX, "table_owner", m_strOwner);
    RFX_Text(pFX, "table_name", m_strTableName);
    RFX_Text(pFX, "column_name", m_strColumnName);
    RFX_Int(pFX, "data_type", m_nDataType);
    RFX_Text(pFX, "type_name", m_strTypeName);
    RFX_Long(pFX, "precision", m_lPrecision);
    RFX_Long(pFX, "length", m_lLength);
    RFX_Int(pFX, "scale", m_nScale);
    RFX_Int(pFX, "radix", m_nRadix);
    RFX_Int(pFX, "nullable", m_nNullable);
    //}}AFX_FIELD_MAP
}