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 ( nametext(20) WITH COMPRESSION not null,
scoredecimal(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, peckermen@163.com, 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 RemarkSQL 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。 |