vc+ado动态创建access数据库

类别:VC语言 点击:0 评论:0 推荐:
vc+ado动态创建access数据库 ado技术目前已经成为连接数据库的主流技术,下面我来介绍如何使用ado来动态创建access数据库。

为了使用ado,必须引入微软的两个动态连接库msadox.dll和msado15.dll:

#pragma warning (disable: 4146)
#import "c:\Program Files\Common Files\system\ado\msadox.dll"
#import "c:\Program Files\Common Files\system\ado\msado15.dll" no_namespace rename("EOF", "EndOfFile")
#pragma warning (default: 4146)

将上述代码加入到stdafx.h文件中,由于ado是com组件,因此使用ado之前还要初始化com环境:

CoInitialize(NULL);



下面是一个在access数据库中创建表的sql语句的例子:

create table test
(
nametext(20) WITH COMPRESSION not null,

scoredecimal(12,4) not null default 0,

ID smallint not null default 0,

birthday date,

sex char(1),

CONSTRAINT CK_CH_SEX Check(SEX in ('N','V')),

CONSTRAINT PK_ID Primary Key (ID)

);



使用ADOX::CatalogPtr来创建mdb文件:

HRESULT hr = S_OK;

//Set ActiveConnection of Catalog to this string
CString strcnn(_T("Provider=Microsoft.JET.OLEDB.4.0;Data source = d:\\test.mdb"));


try
{
ADOX::_CatalogPtr m_pCatalog = NULL;
hr = m_pCatalog.CreateInstance(__uuidof (ADOX::Catalog));

if(FAILED(hr))

 {

_com_issue_error(hr);

 }

 else

 {
m_pCatalog->Create(_bstr_t(strcnn)); //Create MDB

 }
}
catch(_com_error &e)
{
 // Notify the user of errors if any.
 AfxMessageBox(_T(“error“));
}



创建一个连接对象打开刚刚建立的mdb文件:

_ConnectionPtr g_pConn;

g_pConn.CreateInstance(__uuidof(Connection));

g_pConn->Open("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=d:\\test.mdb;",
"", "", adConnectUnspecified);



下面函数用来执行sql文件中的sql语句:

// Function name : RunSqlScript
// Description: 执行SQL脚本, [email protected], 2003-09-15
// Return type: BOOL 成功返回TRUE
// Argument : LPCSTR SqlScriptFile SQL脚本文件名
// Argument : char separator SQL 分割符号, 缺省';'
// Argument : char RemarkSQL 注释符号, 缺省'-'
BOOL RunSqlScript(LPCSTR SqlScriptFile, char separator = ';', char Remark = '-')
{
BOOL bRet = FALSE;
CFileFind finder;
CString ErrLong;
if (finder.FindFile(SqlScriptFile) == TRUE)
{
CFile fSql;
TCHAR *buffer, *pSQL, *p;

fSql.Open(SqlScriptFile,Cfile&::modeRead);
UINT nFileLength = fSql.GetLength();

buffer = (TCHAR *)malloc((nFileLength + 1) * sizeof(TCHAR));
_tcsnset(buffer, TCHAR('\0'), nFileLength + 1);

UINT nBytesRead = fSql.Read(buffer,nFileLength); //把sql文件内容读入内存缓冲区
fSql.Close();

p = pSQL = buffer;
BOOL bRunOK = FALSE;
BOOL bInNote = FALSE;
BOOL bSkip = FALSE;
CString strSQL;
TCHAR ch;
ErrLog = _T("");
while (p < (buffer + nFileLength)){
//判断是否是注释行
 if (bInNote)
 {
if (*p == TCHAR('\x0a'))
 bInNote = FALSE;
 }
 else
 {
if ((*p == Remark) && (*(p+1) == Remark))
{
 bInNote = TRUE;
 p++;
}
else
{
//判断是否是sql语句结束标志
 if (*p == separator){
strSQL = _T("");
bSkip = FALSE;
while (pSQL < p)
{
 if (bSkip == FALSE){
if ((*(pSQL) == Remark) &&(*(pSQL+1) == Remark))
{
 bSkip = TRUE;
 pSQL++;
}
else
{
 ch = *pSQL;
 strSQL = strSQL+ch;
}
 }
 else{
if (*pSQL = TCHAR('\x0a')){
 bSkip = FALSE;
 ch = TCHAR(' ');
 strSQL = strSQL + ch;
}
 }

 pSQL++;
}
pSQL = p + 1;
ErrLog = ErrLog + _T("-- SQL Running ...\n");
ErrLog = ErrLog + strSQL;

_variant_t vRecords;

m_nRecordsAffected = 0;

try
{
 g_pConn->CursorLocation = adUseClient;
 g_pConn->Execute(_bstr_t((LPCTSTR)strSQL), &vRecords, adExecuteNoRecords);
 m_nRecordsAffected = vRecords.iVal;
 bRunOK = TRUE;
}
catch(_com_error &e)
{
 bRunOK = FALSE;
}

if (bRunOK)
 ErrLog = ErrLog + _T("\n-- Successed!\n");
else
{
 ErrLog = ErrLog + _T("\n-- Failed!\n");
 break;
}

 }
}
 }
 p++;
}
free(buffer);
bRet = bRunOK;
}
return bRet;
}



调用RunSqlScript创建access数据库中的表:

RunSqlScript(_T("d:\\test.sql"));



关闭数据库连接:

g_pConn->Close();

::CoUninitialize();



以上代码演示了怎样在vc中利用ado根据sql文件动态创建一个access数据库,欢迎指正。

本文地址:http://com.8s8s.com/it/it219.htm