一个动态生成数据库连接文件的类
作者：肖进

下载本文示例代码

我们知道，数据库连接文件(.udl)可以动态生成各种数据库连接的参数，而且它是一个文本文件。所以我们就可以动态生成，以增强程序的灵活性。但是该文件必须是UNICODE文本文件，不能是普通的ANSI文本文件。因此必须进行数据类型转换。

1、首先定义一个数据库连接结构：

struct db
{
char Server[20];
char Database[20];
char UserId[20];
char Password[20];
};

BOOL CUdlFile::CreateUdlFile(LPCTSTR lpFileName)
{
CFile fUdl;
BOOL bResult;
CString s1,s2,s3;
int m_Length;
//set value
s1="[oledb]";
s2="; Everything after this line is an OLE DB initstring";
s3.Format("Provider=SQLOLEDB.1;Password=%s;Persist Security Info=True;User ID=%s;Initial Catalog=%s;Data Source=%s",
		m_dbParameter.Password,
		m_dbParameter.UserId,
		m_dbParameter.Database,
		m_dbParameter.Server);
//open file
bResult=fUdl.Open (lpFileName,CFile::modeCreate|CFile::modeWrite);
if(!bResult) return FALSE;
LPWSTR  m_Buffer;
m_Buffer = (LPWSTR)malloc(2 * sizeof(WCHAR));
m_Buffer[0]=0xFEFF;  //flag of UNICODE file
fUdl.Write (m_Buffer,2);
free(m_Buffer);
fUdl.Write (L"[oledb]",14); //14为[oldb]的长度X2
fUdl.Write(L"\r\n",4);
fUdl.Write (L"; Everything after this line is an OLE DB initstring",104); //104为字符串长度X2
fUdl.Write(L"\r\n",4);

m_Length=s3.GetLength ();
m_Buffer = (LPWSTR)malloc((m_Length + 1) * sizeof(WCHAR));

MultiByteToWideChar(CP_ACP, 0, s3, m_Length, m_Buffer, m_Length);
fUdl.Write (m_Buffer,s3.GetLength ()*2);
fUdl.Write(L"\r\n",4);

free(m_Buffer);
m_Buffer = NULL;

fUdl.Close ();
return TRUE;
}

BOOL CUdlFile::DeleteUdlFile(LPCTSTR lpFileName)
{
	return ::DeleteFile(lpFileName);
}