dsncollection.cpp

最新visualC++编程200例书籍源码包括对数据库的操作

// DSNCollection.cpp: implementation of the CDSNCollection class.
//
// Author:  Emil Gustafsson ([e-mail])
//          NTier Solutions (www.ntier.se)
// Created: 2000-06-14
//
// Description:
//			This class wraps a few calls to ODBC in order to collect
//			a set of DSNs.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "DSNCollection.h"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

/*static */const unsigned char CDSNCollection::s_SYSTEM = 0x01;
/*static */const unsigned char CDSNCollection::s_USER	= 0x02;

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

CDSNCollection::CDSNCollection() 
	: m_sErrorMsg("")
	, m_iSQLResult(SQL_SUCCESS)
	, m_hSQLEnvironment(SQL_NULL_HANDLE)
{
	// Initialize an environment handle.
	m_iSQLResult = SQLAllocHandle(SQL_HANDLE_ENV,
								  SQL_NULL_HANDLE,
								  &m_hSQLEnvironment);
	if (m_iSQLResult != SQL_SUCCESS)
	{
		m_sErrorMsg = "SQLAllocHandle failed";
		return;
	}

	// Must set the ODBC version we wish to use...
	// Otherwise you will get an error.
	m_iSQLResult = SQLSetEnvAttr(m_hSQLEnvironment,
								 SQL_ATTR_ODBC_VERSION,
								 (SQLPOINTER)SQL_OV_ODBC3,
								 0); //this parameter is ignored when setting ODBC version.
	if (m_iSQLResult != SQL_SUCCESS)
	{
		m_sErrorMsg = "SQLSetEnvAttr failed to set ODBC version";
		return;
	}
}

CDSNCollection::~CDSNCollection()
{
	// Must release the environment handle.
	m_iSQLResult = SQLFreeHandle(SQL_HANDLE_ENV, m_hSQLEnvironment);
}

SQLRETURN CDSNCollection::CallSQLDataSources(CString& sName, SQLUSMALLINT direction)
{
	SQLSMALLINT dataLen1,dataLen2;
	SQLCHAR sTemp[DSNCOLLECTION_BUFLEN];
	SQLCHAR sDesc[DSNCOLLECTION_BUFLEN];

	// This call enumerates the DSNs.
	m_iSQLResult = SQLDataSources(m_hSQLEnvironment, 
								  direction,
								  sTemp,
								  DSNCOLLECTION_BUFLEN,
								  &dataLen1,
								  sDesc,
								  DSNCOLLECTION_BUFLEN,
								  &dataLen2);

	switch (m_iSQLResult)
	{
	case SQL_SUCCESS:			
	case SQL_SUCCESS_WITH_INFO:	
		sName = sTemp;
		break;
	case SQL_NO_DATA: 
		// This is not an error but rather information that there 
		// are no more DSNs to enumerate.
		m_sErrorMsg = "No more DSNs to enumerate";
		break;
	case SQL_ERROR:				
		{
			SQLCHAR sState[10];
			SQLINTEGER iNativeError;
			SQLCHAR sMsg[DSNCOLLECTION_BUFLEN];
			(void)SQLGetDiagRec(SQL_HANDLE_ENV,
								m_hSQLEnvironment,
								1,
								sState,
								&iNativeError,
								sMsg,
								DSNCOLLECTION_BUFLEN,
								&dataLen2);
			m_sErrorMsg.Format("SQL_ERROR: %s:%s",sState,sMsg);
		}
		break;
	case SQL_INVALID_HANDLE:
		m_sErrorMsg = "Invalid Handle";
		break;
	default:
		m_sErrorMsg = "Unknown ERROR";
	}

	return m_iSQLResult;
}


CString CDSNCollection::GetFirstDSNName(unsigned char ucType /* = (s_SYSTEM | s_USER)*/)
{
	CString sResult = "";
	if (ucType != s_SYSTEM &&
		ucType != s_USER &&
		ucType != (s_SYSTEM | s_USER))
	{
		m_sErrorMsg = "Unknown DSN type";
		m_iSQLResult = SQL_ERROR;
	}
	else
	{
		SQLUSMALLINT direction = SQL_FETCH_FIRST;
		if (ucType == s_SYSTEM)
			direction = SQL_FETCH_FIRST_SYSTEM;
		else if (ucType == s_USER)
			direction = SQL_FETCH_FIRST_USER;
		if (SQL_SUCCESS != CallSQLDataSources(sResult, direction))
		{
			//TODO: maybe do something here...
		}
	}

	return sResult;
}

CString CDSNCollection::GetNextDSNName()
{
	CString sResult = "";
	if (SQL_SUCCESS != CallSQLDataSources(sResult, SQL_FETCH_NEXT))
	{
		//TODO: maybe do something here...
	}

	return sResult;
}