#include <iostream>
#include <windows.h>
#include <sqlext.h>
#include <sqltypes.h>
#include <sql.h>
int main()
{
SQLHENV hEnv;
SQLHDBC hDbc;
//SQLCHAR* pwszConnStr = (SQLCHAR*)"Driver={MySQL ODBC 5.1 Driver};Server=127.0.0.1;Port=3306;Database=test;Uid=root;Pwd=xxxx;";
SQLCHAR* pwszConnStr = (SQLCHAR*)"Driver={SQL Server Native Client 11.0};Server=127.0.0.1,1433;Database=master;Uid=sa;Pwd=xxxx;";
SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &hEnv);
SQLSetEnvAttr(hEnv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_OV_ODBC3, 0);
SQLAllocHandle(SQL_HANDLE_DBC, hEnv, &hDbc);
RETCODE rc = SQLDriverConnect(hDbc, NULL, pwszConnStr, SQL_NTS, NULL, 0, NULL, SQL_DRIVER_PROMPT);
if (rc == SQL_SUCCESS)
{
system("pause");
}
}
I follow any codes searched from google. But the RETCODE keeps return -1
Any idea to solve this?
PS:
I have installed all the necessary driver (both 32/64)
The server is Online
Firewall is off
no freetds, sqlapi++
Related
I'm using Microsoft's ODBC driver to connect a C++/Linux application to a SQL Server database running remotely, and when I try to connect to the database, the call fails with SQL_INVALID_HANDLE. Reading through their documentation, I find this:
SQL_INVALID_HANDLE Function failed due to an invalid environment, connection, statement, or descriptor handle. This indicates a programming error. No additional information is available from SQLGetDiagRec or SQLGetDiagField. This code is returned only when the handle is a null pointer or is the wrong type, such as when a statement handle is passed for an argument that requires a connection handle.
Fair enough, but at no point in the creation of the handles and environment prior to the connect statement do I get any errors. Also, for the second argument, their documentation says I can pass in a null pointer if there is no desktop window (as is the case on this linux console application). Here is a MVCE, adapted from Microsoft's example program:
#include "sql.h"
#include "sqlext.h"
#include "msodbcsql.h"
#include <iostream>
#include <string>
int main(int, char**)
{
using std::cerr;
using std::endl;
SQLHENV henv;
SQLHDBC hdbc;
HWND dhandle = nullptr; // no desktop handle in linux
SQLHSTMT hstmt;
SQLRETURN retcode;
SQLCHAR OutConnStr[255];
SQLSMALLINT OutConnStrLen;
retcode = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);
if (!(retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO))
cerr << "SQLAllocHandle (environment) failed " << retcode << endl;
retcode = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER*)SQL_OV_ODBC3, 0);
if (!(retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO))
cerr << "SQLSetEnvAttr failed " << retcode << endl;
retcode = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);
if (!(retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO))
cerr << "SQLAllocHandle (connection) failed " << retcode << endl;
retcode = SQLSetConnectAttr(hdbc, SQL_LOGIN_TIMEOUT, (SQLPOINTER)5, 0);
if (!(retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO))
cerr << "SQLSetConnectAttr failed " << retcode << endl;
std::string dsn = "DRIVER={ODBC Driver 17 for SQL Server};SERVER=*.*.*,1433;DATABASE=***;UID=***;PWD=***";
retcode = SQLDriverConnect(hdbc, dhandle, (SQLCHAR*)dsn.c_str(), dsn.length(), OutConnStr, 255, &OutConnStrLen, SQL_DRIVER_PROMPT);
if (!(retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO))
cerr << "SQLDriverConnect failed " << retcode << endl;
// cleanup code redacted for brevity
return 0;
}
The program outputs SQLDriverConnect failed -2, which is SQL_INVALID_HANDLE. I'm stumped. hdbc is clearly the right type, and examining it in the debugger shows me it is not null.
It may be worth noting that the exact same connection string works in a python program using pyodbc. It seems that the C++ program isn't even getting as far as looking at that string, though. It just doesn't like the handle I'm sending into the connect call.
Microsoft's documentation clearly says they provide no additional information. If anyone can provide any direction on how to diagnose/debug this, I'd appreciate it greatly.
This application uses gcc 4.9.1 on Centos 7.
After two weeks of digging, this turned out to be some kind of versioning problem.
Eventually, this program will be doing some BCP uploads via Microsoft's extensions in libmsodbcsql.so. It turns out that library also has implementations of many of the SQL* functions, which are the ones that are failing in this test program. When I change the order of the link so that libodbc.so is before the MSFT extensions library so that the loader finds those implementations first, the program works fine.
I'm curious why this is, and it probably points to something else I'm doing wrong that may bite me down the road. But for now, at least, I am able to get connected to the database and do basic queries and updates.
Thanks to those who helped.
In Unix does the handle not have to be a non-null value for dialogs to be displayed.
For any handle in SQL Server, it has to be allocated before used!
So the order is Environment, Connection and Statement.
Example:
SQLHENV hEnv = nullptr;
SQLHDBC hDbc = nullptr;
SQLHSTMT hStmt = NULL;
Allocations
SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &hEnv);
SQLAllocHandle(SQL_HANDLE_DBC, hEnv, &hDbc);
SQLAllocHandle(SQL_HANDLE_STMT, hDbc, &hStmt);
Below is sample code that may help you.
Basics fast,
Create table in your sql server database and insert some data
create table test (id int, name nvarchar(128));
Insert some data
insert into test (id,name) values (1, 'Awesome Name');
C++ Code to query items in the table
#include <iostream>
#include <string>
#include <sql.h>
#include <sqlext.h>
int main(int argc, char **argv) {
SQLHENV hEnv = nullptr;
SQLHDBC hDbc = nullptr;
SQLHSTMT hStmt = NULL;
/**
* Allocate environment handle
*/
SQLRETURN allocReturn = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &hEnv);
//Set environment
SQLRETURN setEnvReturn = SQLSetEnvAttr(hEnv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER) SQL_OV_ODBC3, 0);
//Allocate connection handle
SQLAllocHandle(SQL_HANDLE_DBC, hEnv, &hDbc);
SQLCHAR *connection_string = (SQLCHAR *)
"DRIVER={ODBC Driver 17 for SQL Server};SERVER=localhost,1433;DATABASE=database;UID=sa;PWD=password";
//Connect to database
SQLRETURN connReturn = SQLDriverConnect(hDbc, NULL, connection_string, SQL_NTS, NULL, 0, NULL,
SQL_DRIVER_COMPLETE);
//Allocate Statement Handle
SQLAllocHandle(SQL_HANDLE_STMT, hDbc, &hStmt);
//Create statement
SQLCHAR *query = (SQLCHAR *) "SELECT * FROM TEST;";
SQLRETURN sqlPrepareResponse = SQLPrepare(hStmt, query, SQL_NTS); //strlen(reinterpret_cast<const char *>(query))
//Bind columns
SQLCHAR personName[20];
SQLLEN personNameIndex;
SQLRETURN bindNameResponse = SQLBindCol(hStmt, 2, SQL_C_CHAR, personName, sizeof(personName),
&personNameIndex);
SQLINTEGER personId;
SQLLEN personIdIndex;
SQLRETURN personIdBindResponse = SQLBindCol(hStmt, 1, SQL_INTEGER, &personId, 0, &personIdIndex);
SQLRETURN execResponse = SQLExecute(hStmt);
SQLRETURN fetchResponse;
while ((fetchResponse = SQLFetch(hStmt)) != SQL_NO_DATA) {
std::cout << "ID: [" << personId << "] :" << personName << std::endl;
}
/* Free the statement handle. */
SQLFreeHandle(SQL_HANDLE_STMT, hStmt);
/* Disconnect from the database. */
SQLDisconnect(hDbc);
/* Free the connection handle. */
SQLFreeHandle(SQL_HANDLE_DBC, hDbc);
/* Free the environment handle. */
SQLFreeHandle(SQL_HANDLE_ENV, hEnv);
return EXIT_SUCCESS;
}
I have exactly the same error using similar code (that was working in Ubuntu 18.04, but not with a update to 20.04)
cat /etc/odbcinst.ini
[ODBC Driver 17 for SQL Server]
Description=Microsoft ODBC Driver 17 for SQL Server
Driver=/opt/microsoft/msodbcsql17/lib64/libmsodbcsql-17.5.so.2.1
UsageCount=1
using this connection string
DRIVER=ODBC Driver 17 for SQL Server;SERVER=127.0.0.1, 1433;UID=SA;PWD=password;DATABASE=my_database;
this is my library link order
if(UNIX)
find_program(LSB_RELEASE_EXEC lsb_release)
execute_process(COMMAND ${LSB_RELEASE_EXEC} -is OUTPUT_VARIABLE LSB_RELEASE_ID_SHORT OUTPUT_STRIP_TRAILING_WHITESPACE)
message(STATUS "Building in " ${LSB_RELEASE_ID_SHORT})
if("${LSB_RELEASE_ID_SHORT}" STREQUAL "Ubuntu")
message(STATUS "Linking with SQL-Server library")
set(lib_dep ${lib_dep} msodbcsql-17)
endif()
set(lib_dep ${lib_dep} pthread odbc dl)
endif()
As noted in the solution above, changing the link order fixed the problem
set(lib_dep ${lib_dep} pthread odbc dl msodbcsql-17)
The connection string specified is:
Provider=Teradata;DBCName=dbc_name;Database=database_name; Uid=user_name;Pwd=password;
I installed Teradata ODBC client version 15.1 and setup a connection to it via the control panel.
When use the code:
#include "stdafx.h"
#include <Windows.h>
#include <sql.h>
#include <sqlext.h>
#include <string>
int _tmain(int argc, _TCHAR* argv[])
{
SQLHANDLE hdbc = SQL_NULL_HANDLE;
SQLHANDLE henv = SQL_NULL_HANDLE;
SQLRETURN retval = SQL_SUCCESS;
retval = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);
if (retval != SQL_SUCCESS) {
printf("SQLAllocHandle SQL_HANDLE_ENV failed! Result = %d\n", retval);
}
retval = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_OV_ODBC3, 0);
if (retval != SQL_SUCCESS) {
printf("SQLSetEnvAttr SQL_ATTR_ODBC_VERSION failed! Result = %d\n", retval);
}
SQLINTEGER output_nts, autocommit;
retval = SQLGetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, &output_nts, 0, 0);
retval = SQLSetEnvAttr(henv, SQL_ATTR_OUTPUT_NTS, (SQLPOINTER)SQL_TRUE, 0);
if (retval != SQL_SUCCESS) {
printf("SQLSetEnvAttr SQL_ATTR_OUTPUT_NTS failed! Result = %d\n", retval);
}
retval = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);
if (retval != SQL_SUCCESS) {
printf("SQLAllocHandle SQL_HANDLE_DBC failed! Result = %d\n", retval);
}
SQLCHAR szConn[1024];
SWORD cbConn = 0;
std::string connectionString("Provider=teradata;DBCName=myLocalTDcop;database=myDatabaseName;uid=myUID;pwd=myPwd;");
retval = SQLDriverConnect(hdbc, NULL, (SQLCHAR*)connectionString.c_str(), SQL_NTS, szConn, 1024, &cbConn, SQL_DRIVER_NOPROMPT);
if (retval != SQL_SUCCESS) {
printf("SQLDriverConnect failed! Result = %d\n", retval);
}
}
The SQLDriverConnect command always returns -1.
Am I doing something wrong with the connection string?
Update:
Using SQLGetDiagRec I have obtained the error message:
The driver returned invalid (or failed to return) SQL_DRIVER_ODBC_VER: 03.80
However, if I change the ODBC version to SQL_OV_ODBC3_80 then I get the error message:
[Microsoft][ODBC Driver Manager] The driver doesn't support the version of ODBC behavior that the application requested (see SQLSetEnvAttr).
and then:
The driver returned invalid (or failed to return) SQL_DRIVER_ODBC_VER: 03.80
Is this to do with the ODBC version of 15.10? I have looked at the documentation but cannot see where the ODBC version is specified. Is there a way to check it in Windows?
I had not added the correct directory to the Path environmental variable!!!!
Greeting guys , I have been looking on the internet on how to connect C++ code with SQLEXPRESS DATABASE, I have read some threads about how to connect but yet... I CAN NOT follow any of them... neither they are working for me.
I dont want to use MFC or any kind of C++ methods for DB , I want to do it via raw coding.
problem:
the Database connectable via Visual studio and via Microsoft SQL
Server Studio , I can add or drop tables as I LIKE, I believe the DB
as it is, is working fine
the C++ code is here " I am Connecting to a local DB "
I got this code from one of the threads and was not able to figure out how to do the SQLDriverConnect,
I am very noob in C++... adding SQLEXPRESS on top of that...
edit:
I dont know what that 3055 in the connect code is...
thank you in advance for help
Data base information:
UDL:
this what I got from the udl
( Provider=SQLOLEDB.1;Integrated Security=SSPI;
Persist Security Info=False;User ID=sa;Initial Catalog=Holpa;Data Source=AMH )
Microsoft server:
Server type: Database Engine
Server name: AMH
Authen: SQL server Authen
Login: sa
password : amh999
VisualStudio:
Data Source=AMH;Initial Catalog=Holpa;User ID=sa;Password=***********
.NET Framework Data Provider for SQL Server
Open
Microsoft SQL Server
Owner sa
running on local machine.
#include <iostream>
#include <windows.h>
#include <sqltypes.h>
#include <sql.h>
#include <sqlext.h>
using namespace std;
SQLHANDLE sqlenvhandle = SQL_NULL_HANDLE;
SQLHANDLE sqlconnectionhandle = SQL_NULL_HANDLE;
SQLHANDLE sqlstatementhandle = SQL_NULL_HANDLE;
SQLRETURN retcode;
void show_error(RETCODE rc, SQLHENV hEnv, SQLHDBC hDbc,
SQLHSTMT hStmt, const char *action)
{
SQLWCHAR szMessage[256];
SQLWCHAR szState[6];
SDWORD sdwNative;
SWORD swMsgLen;
SQLError(hEnv, hDbc, hStmt, szState, &sdwNative, szMessage,
sizeof(szMessage), &swMsgLen);
wcout << "wcout MESSAGE: " << szMessage << "\n SQLSTATE " << szState << endl;
printf("Error %d performing %s\n SQLState=%s\nSQL message=%s\n",rc, action, szState, szMessage);
}
void CloseSQL()
{
SQLFreeHandle(SQL_HANDLE_STMT, sqlstatementhandle);
SQLDisconnect(sqlconnectionhandle);
SQLFreeHandle(SQL_HANDLE_DBC, sqlconnectionhandle);
SQLFreeHandle(SQL_HANDLE_ENV, sqlenvhandle);
}
int main()
{
if (SQL_SUCCESS != SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &sqlenvhandle))
{
printf("huh \n");
CloseSQL();
goto END;
}
if (SQL_SUCCESS != SQLSetEnvAttr(sqlenvhandle, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_OV_ODBC3, 0))
{
printf("huh \n");
CloseSQL();
goto END;
}
if (SQL_SUCCESS != SQLAllocHandle(SQL_HANDLE_DBC, sqlenvhandle, &sqlconnectionhandle))
{
printf("huh \n");
CloseSQL();
goto END;
}
printf("Driver Initialised\n");
SQLWCHAR retconstring[1024];
printf("about to Driver Conneect\n");
retcode = SQLDriverConnect(sqlconnectionhandle,
NULL,
(SQLWCHAR*)"DRIVER={SQL Server};SERVER=AMH, 3055;DATABASE=Holpa;UID=sa;PWD=amh999;",
SQL_NTS,
retconstring,
1024,
NULL,
SQL_DRIVER_NOPROMPT);
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO)
{
printf("Connection made\n");
}
else
{
show_error(retcode, sqlenvhandle, sqlconnectionhandle, sqlstatmenthandle, "Connecting.");
}
END:
printf("\n");
printf("Program End, press enter key to exit!");
getchar(); // waits for input
return 0;
}
ERRORS:
the error codes are not constants... they keep changing ... example I got the following:
Message: 0022E1EC
SQLSTATE: 0022e9f4
re-run the program
Message: 009fdc4c
SQLSTATE: 009fe454
rerun the code
Message: 00aadd90
SQLSTATE: 00aae598
Firstly, you need a diagonostic function that works:
void show_error(RETCODE rc, SQLHENV hEnv, SQLHDBC hDbc,
SQLHSTMT hStmt, const char *action)
{
char szMessage[256];
char szState[6];
SDWORD sdwNative;
SWORD swMsgLen;
SQLError(hEnv, hDbc, hStmt, szState, &sdwNative, szMessage,
sizeof(szMessage), &swMsgLen);
printf("Error %d performing %s\n"
"SQLState=%s\nSQL message=%s\n",
rc, action, szState, szMessage);
}
Then call it if anything goes wrong, e.g.:
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO)
{
printf("Connection made\n");
}
else
{
show_error(retcode, sqlenvhandle, sqlconnectionhandle, sqlstatmenthandle, "Connecting.");
}
Database: Microsoft SQL Server - any version
Preferably the easiest way (without connecting third-party libraries). You just need to test connectivity
In the task cannot be used .Net Framework and it is not advisable to MFC
The project in Visual Studio 2008 Professional
CDatabase * db = new CDatabase ();
if (!db->OpenEx (args [2], CDatabase::noOdbcDialog))
{
printf ("Failed to connect to DB\n");
ExitProcess (1);
}
db->Close();
This code on the MFC is not suitable because it requires the installation of Redistributable.
It is desirable to use the WinAPI.
Thank you for your attention.
UPD:
SQLHANDLE hEnv, hDbc;
SQLAllocHandle (SQL_HANDLE_ENV, SQL_NULL_HANDLE, &hEnv);
SQLSetEnvAttr (hEnv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER) SQL_OV_ODBC3, NULL);
SQLAllocHandle (SQL_HANDLE_DBC, hEnv, &hDbc);
LPSTR lpConnectionString = args [2];
LPSTR lpOutputString = new CHAR [256];
SQLSMALLINT sLength;
SQLRETURN sqlRet = SQLDriverConnect(hDbc, 0, (SQLCHAR*)lpConnectionString, strlen (lpConnectionString), (SQLCHAR*)lpOutputString, 255, &sLength, SQL_DRIVER_NOPROMPT);
args[2] = "DRIVER={SQL Server};SERVER={VM7\SQLEXPRESS};Database={master}";
VM7 is name of my machine
There are only 2 'Native' database libraries that ship with Windows. They are ODBC and OLEDB. Given that OLEDB is a COM based interface and requires significantly more knowledge I'm only going to discuss the ODBC solution here.
The code below is bare bones and is there only to provide hints on how to solve the problem.
#include <Windows.h>
#include <sql.h>
#include <sqlext.h>
#include <sqltypes.h>
#define MAX_STRING_LEN 255
int main()
{
SQLHANDLE henv, hdbc;
SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);
SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_ODBC_VER, SQL_IS_INTEGER);
SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);
wchar_t* connection_string = L"Driver={SQL Server};Server=<address>;Database=<database name>;Uid=<username>;Pwd=<password>";
wchar_t output_string[MAX_STRING_LEN + 1];
SQLSMALLINT out_length;
SQLDriverConnect(hdbc, 0, connection_string, lstrlen(connection_string), output_string, MAX_STRING_LEN, &out_length, SQL_DRIVER_NOPROMPT);
}
My subject is somewhat stupid and complex for me. I'm trying to make a very simple connection with an Access 2007 db, but the connection never happens. I'm trying to see what happens with SQLGetDiagRec(), but the program crashes when SQLGetDiagRec() is executed. I'm not that much into C++, so I'm stuck for the past few days in this. Any help will be highly appreciated. I'm using Visual C++ 2008.
EDIT: After changing the character set from Unicode to Multibyte, I was able to execute the SQLGetDiagRec. I, then, changed my two pointers from int and char to SQLSMALLINT and SQLCHAR and, bam, it worked. Thanx a lot for the heads up guys.
#include "stdafx.h"
#include <windows.h>
#include <conio.h>
#include <iostream>
#include <sql.h>
#include <sqltypes.h>
#include <sqlext.h>
#include <stdio.h>
#include <stdlib.h>
int main(){
char szDSN[256] = "DRIVER={Microsoft Access Driver (*.mdb, *.accdb)};DSN='Hospital_mdb';DBQ=C:\\Hospital.mdb;";
SQLHANDLE EnvHandlePtr;
SQLHANDLE ConHandle;
SQLHANDLE StmtHandle;
SQLRETURN rc;
SQLSMALLINT iConnStrLength2Ptr; // Changing from int iConnStrLength2Ptr;
SQLCHAR szConnStrOut[256]; //changing from char szConnStrOut[256];
SQLCHAR SQLState[6], Msg[SQL_MAX_MESSAGE_LENGTH];
SQLINTEGER NativeError;
SQLSMALLINT MsgLen;
if ( (rc = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &EnvHandlePtr)) == SQL_SUCCESS){
printf("Environment Set!");
if( (rc = SQLSetEnvAttr(EnvHandlePtr, SQL_ATTR_ODBC_VERSION,
(SQLPOINTER) SQL_OV_ODBC3, SQL_IS_UINTEGER))==SQL_SUCCESS ){
printf("Driver Set!");
if ( (rc = SQLAllocHandle(SQL_HANDLE_DBC, EnvHandlePtr, &ConHandle))==SQL_SUCCESS ){
printf("Allocation Done!");//**so far, so good, but then the connection doesn't happen**
rc = SQLDriverConnect(ConHandle, NULL, (SQLWCHAR*)szDSN,
SQL_NTS, (SQLWCHAR*) szConnStrOut, 0, (SQLSMALLINT*) iConnStrLength2Ptr, SQL_DRIVER_NOPROMPT);
if ( rc == SQL_SUCCESS ){
//if ( (rc = SQLConnect(ConHandle, (SQLWCHAR*)szDSN, SQL_NTS, (SQLWCHAR*)"", SQL_NTS, (SQLWCHAR*)"", SQL_NTS))== SQL_SUCCESS ){
printf("Connection Done");
}//end of Connection clause
else{
SQLGetDiagRec(SQL_HANDLE_DBC, ConHandle, 1, (SQLWCHAR*)SQLState, &NativeError, (SQLWCHAR*)Msg, sizeof(Msg), &MsgLen);
printf("Connection Failed\n%s", Msg);
}
SQLDisconnect(ConHandle);
}//end of Connection Allocation clause
SQLFreeHandle(SQL_HANDLE_DBC, ConHandle);
}//end of Driver clause
SQLFreeHandle(SQL_HANDLE_ENV, EnvHandlePtr);
}//end of Enviroment clause
_getch();
}//end of main
You are casting the diagnostics that the compiler generates for your bad code away. At least SQLState is bad, you are passing a 6 byte buffer when 12 bytes are written. That corrupts the stack frame. The SQLDriverConnect call cannot work for the same reason.
Remove all casts by declaring your local variables properly.
And use Unicode in your code. You could disable it in your project settings but that's never not a mistake when you work with a dbase.