Visual Studio C++ connect to DB2 - c++

Question

I'm trying to write a C ++ program using a database - IBM DB2 Express-C. Also, I use Visual Studio 2015. Via IBM OLE DB Provider for DB2 my Visual Studio successfully connected to DB2. I can see tables and all OK:
Then I created new C++ program, I successfully connect several header files, some from them I found in my DB2 directory, for example sqlcli1.h
#pragma once
#include "targetver.h"
#include <stdio.h>
#include <tchar.h>
#include <stdlib.h>
#include <string.h>
#include <sqlcli1.h>
#include <windows.h>
The following is the code of the main program. In which I am trying to connect to the database to which successfully was connected the Visual Studio.
#include "stdafx.h"
int main()
{
SQLHENV henv;
SQLHDBC hdbc;
SQLHSTMT hstmt;
SQLRETURN retcode;
SQLCHAR * OutConnStr = (SQLCHAR *)malloc(255);
SQLSMALLINT * OutConnStrLen = (SQLSMALLINT *)malloc(255);
// 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) {
// Allocate connection handle
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) {
retcode = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);
// Connect to data source
retcode = SQLConnect(hdbc, (SQLWCHAR*) "DATABASE=SAMPLE;HOSTNAME=localhost", SQL_NTS, (SQLWCHAR*) "db2admin", SQL_NTS, (SQLWCHAR*) "password", SQL_NTS);
if (retcode != SQL_SUCCESS) {
printf(">--- Error while connecting to database:");
printf("SQLConnect: %d\n", retcode);
}
// Allocate statement handle
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) {
retcode = SQLAllocHandle(SQL_HANDLE_STMT, hdbc, &hstmt);
printf("\nAllocate Connection handle successfully.");
// Process data
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) {
SQLFreeHandle(SQL_HANDLE_STMT, hstmt);
}
SQLDisconnect(hdbc);
}
SQLFreeHandle(SQL_HANDLE_DBC, hdbc);
}
SQLFreeHandle(SQL_HANDLE_ENV, henv);
}
system("pause");
return 0;
}
There are no errors at compile time, but can not connect to the database.When program execution comes to the block.
// Connect to data source
retcode = SQLConnect(hdbc, (SQLWCHAR*) "DATABASE=SAMPLE;HOSTNAME=localhost", SQL_NTS, (SQLWCHAR*) "db2admin", SQL_NTS, (SQLWCHAR*) "password", SQL_NTS);
if (retcode != SQL_SUCCESS) {
printf(">--- Error while connecting to database:");
printf("SQLConnect: %d\n", retcode);
}
I see >--- Error while connecting to database:SQLConnect:-2
What does it means? what I am doing is wrong? I also tried it:
retcode = SQLConnect(hdbc, (SQLWCHAR*) "SAMPLE", SQL_NTS, (SQLWCHAR*) "db2admin", SQL_NTS, (SQLWCHAR*) "password", SQL_NTS);
But it also does not work. May be the second argument should look like in some other way?
Changed
I tried use this function SQLGetDiagRec I created some variables
SQLWCHAR SqlState[6], SQLStmt[100], Msg[SQL_MAX_MESSAGE_LENGTH];
SQLINTEGER NativeError;
SQLSMALLINT i, MsgLen;
SQLRETURN rc1, rc2;
I also change my connect block
// Connect to data source
retcode = SQLConnect(hdbc, (SQLWCHAR*) "SAMPLE", SQL_NTS, (SQLWCHAR*) "db2admin", SQL_NTS, (SQLWCHAR*) "password", SQL_NTS);
if (retcode != SQL_SUCCESS) {
printf(">--- Error while connecting to database:");
printf("SQLConnect: %d\n", retcode);
if ((retcode == SQL_SUCCESS_WITH_INFO) || (retcode == SQL_ERROR)) {
// Get the status records.
i = 1;
while ((rc2 = SQLGetDiagRec(SQL_HANDLE_STMT, hdbc, i, SqlState, &NativeError,
Msg, sizeof(Msg), &MsgLen)) != SQL_NO_DATA) {
cout << SqlState;
cout << i;
cout << NativeError;
cout << Msg;
i++;
}
}
}
But nothing has changed. Does anyone have any idea?

Answer 1

If a call to any CLI function doesn't return SQL_SUCCESS, then your error handling should use SQLGetDiagRec() to get the details of the warning or error.
Documentation: SQLGetDiagRec