最近在使用 MFC 連接 MySQL 數據庫時出現了連接失敗的情況，經過多次嘗試，總結了以下幾點可能的原因。

// 嘗試連接數據庫
CDatabase database;
CString sDsn;
sDsn.Format(_T("ODBC;DRIVER={MySQL ODBC 5.3 ANSI Driver};SERVER=%s;UID=%s;PWD=%s;DATABASE=%s;PORT=%d"),
SERVERNAME, USERNAME, PASSWORD, DATABASE, PORT);
TRY {
database.Open(NULL, FALSE, FALSE, sDsn);
} CATCH (CDBException, e) {
// 輸出連接失敗的錯誤信息
AfxMessageBox(e->m_strError);
} END_CATCH

1. MySQL ODBC 驅動未安裝或版本不匹配

// 在注冊表中查找 MySQL ODBC 驅動是否安裝
HKEY hKey = NULL;
if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, _T("SOFTWARE\\ODBC\\ODBCINST.INI\\MySQL ODBC 5.3 ANSI Driver"), 0, KEY_QUERY_VALUE, &hKey) != ERROR_SUCCESS) {
// 驅動未安裝
AfxMessageBox(_T("MySQL ODBC 5.3 ANSI Driver not found, please install it first!"));
}
else {
// 驗證驅動版本是否匹配
TCHAR szPath[MAX_PATH] = { 0 };
DWORD dwSize = sizeof(szPath);
if (RegQueryValueEx(hKey, _T("Driver"), NULL, NULL, (LPBYTE)szPath, &dwSize) != ERROR_SUCCESS) {
// 無法獲取驅動路徑
AfxMessageBox(_T("Can't find MySQL ODBC driver path, please reinstall it!"));
}
else {
// 判斷驅動版本是否匹配
CString sDriverVersion = _T("");
GetModuleVersion(szPath, sDriverVersion);
if (sDriverVersion != _T("5.3.13.0")) {
AfxMessageBox(_T("MySQL ODBC driver version does not match, please install version 5.3.13.0!"));
}
}
RegCloseKey(hKey);
}

2. MySQL 服務未啟動或端口異常

// 查詢 MySQL 服務狀態是否正常
SC_HANDLE hSCM = OpenSCManager(NULL, NULL, SC_MANAGER_CONNECT);
if (hSCM == NULL) {
AfxMessageBox(_T("Failed to open Service Control Manager!"));
}
else {
SC_HANDLE hService = OpenService(hSCM, _T("MySQL"), SERVICE_QUERY_STATUS);
if (hService == NULL) {
AfxMessageBox(_T("Failed to open MySQL service!"));
}
else {
SERVICE_STATUS ss = { 0 };
if (QueryServiceStatus(hService, &ss)) {
if (ss.dwCurrentState != SERVICE_RUNNING) {
AfxMessageBox(_T("MySQL service is not running, please start it!"));
}
}
else {
AfxMessageBox(_T("Failed to query MySQL service status!"));
}
CloseServiceHandle(hService);
}
CloseServiceHandle(hSCM);
}
// 檢查連接端口是否正常
if (IsPortOpened(SERVERNAME, PORT) == FALSE) {
AfxMessageBox(_T("MySQL port is not opened, please check firewall or network settings!"));
}

3. 數據連接字符串有誤

// 確保服務器地址、用戶名、密碼、數據庫名、端口號等連接參數正確
CString sDsn;
sDsn.Format(_T("ODBC;DRIVER={MySQL ODBC 5.3 ANSI Driver};SERVER=%s;UID=%s;PWD=%s;DATABASE=%s;PORT=%d"),
SERVERNAME, USERNAME, PASSWORD, DATABASE, PORT);

以上是我在解決 MFC 連接 MySQL 數據庫無法成功的過程中總結的一些可能出現的問題，僅供參考！