Is there a way to query .accdb/.mdb files with C++? - c++

Question

I have a school project where I need to develop an application that queries and writes into Access database files, but using C++.
After some research I found about ODBC, and that it could help me, but I had no luck. I've tried differents connection strings, but nothing seems to work.
What I've done so far:
#include "pch.h"
#include <windows.h>
#include <sqlext.h>
#include <stdio.h>
#include <stdlib.h>
int main()
{
char szDSN[256] = "Driver={Microsoft Access Driver (*.mdb,
*.accdb)};DBQ=C:\\EntrySystem.mdb";
/* Data Access Method used in this sample */
const char* DAM = "Direct ODBC";
HENV hEnv;
HDBC hDbc;
/* ODBC API return status */
RETCODE rc;
int iConnStrLength2Ptr;
char szConnStrOut[256];
unsigned char query[] = "SELECT * from Condomino;";
SQLCHAR chval1[128], chval2[128], colName[128];
int ret1;
int ret2;
/* Number of rows and columns in result set */
SQLINTEGER rowCount = 0;
SQLSMALLINT fieldCount = 0, currentField = 0;
HSTMT hStmt;
/* Allocate an environment handle */
rc = SQLAllocEnv(&hEnv);
/* Allocate a connection handle */
rc = SQLAllocConnect(hEnv, &hDbc);
/* Connect to the 'Northwind 2007.accdb' database */
rc = SQLDriverConnect(hDbc, NULL, (SQLWCHAR*)szDSN,
SQL_NTS, (SQLWCHAR*)szConnStrOut,
255, (SQLSMALLINT*)&iConnStrLength2Ptr, SQL_DRIVER_NOPROMPT);
if (SQL_SUCCEEDED(rc))
{
printf("%s: Successfully connected to database. Data source name: \n %s\n",
DAM, szConnStrOut);
/* Prepare SQL query */
printf("%s: SQL query:\n %s\n", DAM, query);
rc = SQLAllocStmt(hDbc, &hStmt);
rc = SQLPrepare(hStmt, (SQLWCHAR*)query, SQL_NTS);
/* Bind result set columns to the local buffers */
rc = SQLBindCol(hStmt, 1, SQL_C_CHAR, chval1, 128, (SQLINTEGER*)&ret1);
rc = SQLBindCol(hStmt, 2, SQL_C_CHAR, chval2, 128, (SQLINTEGER*)&ret2);
/* Excecute the query and create a record set */
rc = SQLExecute(hStmt);
if (SQL_SUCCEEDED(rc))
{
printf("%s: Retrieve schema info for the given result set:\n", DAM);
SQLNumResultCols(hStmt, &fieldCount);
if (fieldCount > 0)
{
for (currentField = 1; currentField <= fieldCount; currentField++)
{
SQLDescribeCol(hStmt, currentField,
(SQLWCHAR*)colName, sizeof(colName), 0, 0, 0, 0, 0);
printf(" | %s", colName);
}
printf("\n");
}
else
{
printf("%s: Error: Number of fields in the result set is 0.\n", DAM);
}
printf("%s: Fetch the actual data:\n", DAM);
/* Loop through the rows in the result set */
rc = SQLFetch(hStmt);
while (SQL_SUCCEEDED(rc))
{
printf(" | %s | %s\n", chval1, chval2);
rc = SQLFetch(hStmt);
rowCount++;
};
printf("%s: Total Row Count: %d\n", DAM, rowCount);
rc = SQLFreeStmt(hStmt, SQL_DROP);
}
}
else
{
printf("%s: Couldn't connect to %s.\nLastError: %d\n", DAM, szDSN, GetLastError());
}
/* Disconnect and free up allocated handles */
SQLDisconnect(hDbc);
SQLFreeHandle(SQL_HANDLE_DBC, hDbc);
SQLFreeHandle(SQL_HANDLE_ENV, hEnv);
printf("%s: Cleanup. Done.\n", DAM);
return 0;
}
I expect it to query all rows from my table "condomino", but the library (sqlext) keep giving me the error "0". Any help would be welcome, if you any other solutions, let me know.

Answer 1

Yes.
Seems like you are having issue with Access connection strings. An alternative is to create User DNS ; go to control panel / administrative tools / ODBC Data Source / choose Microsoft Access Database - configure and set your path to your *.mdb ( use of *.accdb recommended)
Now your connection string will be simplified as ( driver name is case sensitive ):
SQLWCHAR outstr[1024];
SQLSMALLINT outstrlen;
SQLReturnCode = SQLDriverConnect(hDatabase, NULL, L"DSN=Microsoft Access Driver;", SQL_NTS,
outstr, sizeof(outstr), &outstrlen, SQL_DRIVER_COMPLETE);