columnst.cpp

用ODBC对数据库实现连接 显示数据 修改数据

// sqlcols.cpp: implementation of the CColumns class
//
// This is a part of the Microsoft Foundation Classes C++ library.
// Copyright (C) 1992-1998 Microsoft Corporation
// All rights reserved.
//
// This source code is only intended as a supplement to the
// Microsoft Foundation Classes Reference and related
// electronic 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* pDatabase)
	: CRecordset(pDatabase)
{
	//{{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(LPCSTR pszTableQualifier /* = NULL */, LPCSTR pszTableOwner /* = NULL */,LPCSTR pszTableName /* = NULL */,LPCSTR pszColumnName /* = NULL */,UINT nOpenType /* = forwardOnly */)
{
	RETCODE nRetCode; 
	UWORD bFunctionExists; 
	//检验是否支持SQLColumns函数 
	AFX_SQL_SYNC(::SQLGetFunctions(m_pDatabase->m_hdbc,SQL_API_SQLCOLUMNS,&bFunctionExists)); 
	if (!Check(nRetCode) || !bFunctionExists) 
	{ 
		if (!bFunctionExists) 
			TRACE(_T("SQLColumns 不支持\n")); 
		return FALSE; 
	} 
	//设置缓冲区状态，分配语句句柄 
	SetState(nOpenType,NULL,readOnly); 
	if (!AllocHstmt()) 
		return FALSE; 
	TRY 
	{ 
		OnSetOptions(m_hstmt); 
		AllocStatusArrays(); 
		// 调用ODBC的SQLColumns函数 
		AFX_ODBC_CALL(::SQLColumns(m_hstmt, 
			(UCHAR FAR*)pszTableQualifier,SQL_NTS, 
			(UCHAR FAR*)pszTableOwner,SQL_NTS, 
			(UCHAR FAR*)pszTableName,SQL_NTS, 
			(UCHAR FAR*)pszColumnName,SQL_NTS)); 
		if (!Check(nRetCode)) 
			ThrowDBException(nRetCode,m_hstmt); 
		// 分配内存，填写信息 
		AllocAndCacheFieldInfo(); 
		AllocRowset(); 
		MoveNext(); 
		m_bBOF = m_bEOF; 
	} 
	//异常信息的捕获 
	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
}