我有以下代碼(使用ODBC連接到一個SQL數據庫): 連接正常,也是第一個SQL_ExecuteQuery(),但第二個和第三個SQL_ExecuteQuery()將返回一個錯誤(SQLExecDirect的返回碼-1 )。 我假設,「語句句柄hstmt」將在第一次執行後被覆蓋。但我怎麼能避免這種情況?非常感謝。如何設置ODBC連接以在C++中執行多個查詢(SQLExecDirect)?
SQLHENV henv = SQL_NULL_HENV;
SQLHDBC hdbc = SQL_NULL_HDBC;
SQLHDBC hstmt= SQL_NULL_HSTMT;
SQLRETURN retcode = SQL_SUCCESS;
//Connect function
int SQL_Connect()
{
SQLWCHAR OutConnStr[255];
SQLSMALLINT OutConnStrLen;
// Allocate environment handle
retcode = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);
// Set the ODBC version environment attribute
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO)
{
retcode = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER*)SQL_OV_ODBC3, 0);
// Allocate connection handle
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO)
{
retcode = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);
// Set login timeout to 5 seconds
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO)
{
SQLSetConnectAttr(hdbc, SQL_LOGIN_TIMEOUT, (SQLPOINTER)5, 0);
retcode = SQLDriverConnect(hdbc,
NULL,
#ifdef IPC
(SQLWCHAR *)L"DSN=TEST;Description=ODK;UID=FFF;PWD=XXX;Trusted_Connection=No;DATABASE=DDD;",
#else
(SQLWCHAR *)L"DSN=ODKSQL64;Description=ODK;UID=auto;PWD=Visu_KDbos;Trusted_Connection=No;DATABASE=Giesserei_BKO;",
#endif
SQL_NTS,
OutConnStr,
255,
&OutConnStrLen,
SQL_DRIVER_NOPROMPT);
// Allocate statement handle
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO)
{
retcode = SQLAllocHandle(SQL_HANDLE_STMT, hdbc, &hstmt);
cout<<"Verbindung OK"<<std::endl;
}
}
}
}
return retcode;
}
//Disonnect function
int SQL_Disconnect()
{
SQLFreeHandle(SQL_HANDLE_STMT, hstmt);
SQLDisconnect(hdbc);
SQLFreeHandle(SQL_HANDLE_DBC, hdbc);
SQLFreeHandle(SQL_HANDLE_ENV, henv);
return 1;
}
//Query function
int SQL_ExecuteQuery()
{
short rc;
char material[50];
SQLINTEGER strlenmaterial;
//prepare query
std::wstring SQL_Statement = L"SELECT blablabla";
rc = SQLExecDirect(hstmt, const_cast<SQLWCHAR*>(SQL_Statement.c_str()), SQL_NTS);
if (rc==SQL_SUCCESS || rc==SQL_SUCCESS_WITH_INFO) {
SQLBindCol(hstmt, 1, SQL_C_CHAR, &material, (SQLINTEGER) sizeof(material), &strlenmaterial);
while (1) {
rc = SQLFetch(hstmt);
if (rc==SQL_SUCCESS || rc==SQL_SUCCESS_WITH_INFO) {
rc = 1;
}else {
break;
}
}
} else {
//no data found
rc = 3;
}
return rc;
}
int main()
{
short rc;
rc = SQL_Connect();
rc = SQL_ExecuteQuery();
rc = SQL_ExecuteQuery();
rc = SQL_ExecuteQuery();
rc = SQL_Disconnect();
return 0;
}
非常感謝您的回答。現在一切正常。 – Osti
@Osti:歡迎。你能接受它作爲答案嗎,要說清楚它解決了你的問題? – erg