SQL Server 2017 C++ ODBC connection not working on Linux

Question

We are using an Azure SQL Server 2017 database and wish to connect to it via c++. We have already achieved this incredible feat on windows but it is necessary to run this on ubuntu.

We installed the Linux ODBC 13 driver using this tutorial and our /etc/odbcinst.ini file contains the following

[ODBC Driver 13 for SQL Server]
Description=Microsoft ODBC Driver 13 for SQL Server
Driver=/opt/microsoft/msodbcsql/lib64/libmsodbcsql-13.0.so.1.0
UsageCount=1

[ODBC]
Trace = Yes
TraceFile = /dev/stdout

Our code is as follows:

#include <iostream>
#include <string>
#include <sqlext.h>
#include <sqltypes.h>
#include <sql.h>
#include <stdio.h>

using namespace std;

int main() {

    #define SQL_RESULT_LEN 240
    #define SQL_RETURN_CODE_LEN 1024

    //define handles and variables
    SQLHDBC      hdbc = SQL_NULL_HDBC;   // Connection handle
    SQLHANDLE    sqlConnHandle = NULL;
    SQLHANDLE    sqlStmtHandle = NULL;
    SQLHANDLE    sqlEnvHandle;
    SQLCHAR      outstr[SQL_RETURN_CODE_LEN];
    SQLRETURN    retcode;
    SQLSMALLINT  outstrlen;

    //allocations
    if (SQL_SUCCESS != SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &sqlEnvHandle))
        cout << "SQLAllocHandle err (ENV)" << endl;

    if (SQL_SUCCESS != SQLSetEnvAttr(sqlEnvHandle, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_OV_ODBC3, 0))
        cout << "SQLSetEnvAttr err" << endl;

    if (SQL_SUCCESS != SQLAllocHandle(SQL_HANDLE_DBC, sqlEnvHandle, &sqlConnHandle))
        cout << "SQLAllocHandle (DBC) err" << endl;

    //output
    cout << "Attempting connection to SQL Server..." << endl;

    //Connect to server

    retcode = SQLDriverConnect(hdbc, NULL, (SQLCHAR *)"Driver={ODBC Driver 13 for SQL Server};Server=tcp:cppdatabase.database.windows.net,1433;Database=stockData;Uid=admin@cppdatabase;Pwd=password;Encrypt=yes;TrustServerCertificate=no;Connection Timeout=30;", SQL_NTS, outstr, sizeof(outstr), &outstrlen, SQL_DRIVER_NOPROMPT);

    switch (retcode) {

    case SQL_SUCCESS:
        cout << "Successfully connected to SQL Server" << endl;
        break;

    case SQL_SUCCESS_WITH_INFO:
        cout << "Successfully connected to SQL Server"<< endl;
        break;

    case SQL_INVALID_HANDLE:
        cout << "Could not connect to SQL Server" << endl;
        break;

    case SQL_ERROR:
        cout << "Could not connect to SQL Server ERR" << endl;
        break;

    default:
        break;
    }
}

Which we compile with g++ as follows: g++ -g mssql.cpp -fpermissive -lodbc -o mssql

This code however fails to connect and we get the following output (no compiling errors):

[ODBC][17915][1559000402.543184][__handles.c][460]
        Exit:[SQL_SUCCESS]
            Environment = 0xf04d10
[ODBC][17915][1559000402.543204][SQLSetEnvAttr.c][189]
        Entry:
            Environment = 0xf04d10
            Attribute = SQL_ATTR_ODBC_VERSION
            Value = 0x3
            StrLen = 0
[ODBC][17915][1559000402.543216][SQLSetEnvAttr.c][363]
        Exit:[SQL_SUCCESS]
[ODBC][17915][1559000402.543223][SQLAllocHandle.c][375]
        Entry:
            Handle Type = 2
            Input Handle = 0xf04d10
[ODBC][17915][1559000402.543232][SQLAllocHandle.c][493]
        Exit:[SQL_SUCCESS]
            Output Handle = 0xf05610
Attempting connection to SQL Server...
[ODBC][17915][1559000402.543250][SQLDriverConnect.c][686]Error: SQL_INVALID_HANDLE
Could not connect to SQL Server
Could not connect to SQL Server ERR

The connection string we used came directly from the Azure portal (while the sensitive data has been replaced with generic variants) so we doubt there is any issue with that. We doubt it is a driver issue as ODBC successfully logs to stdout. So we imagine it must be a coding problem.

Any pointers (no pun intended)?

Answer 1

We solved it using a Domain Source Name (DNS). In our /etc/odbc.ini file we wrote:

[mssql]
Description = "Test for Microsoft SQL Server 2017 using ODBC 2013 driver"
Driver = /opt/microsoft/msodbcsql/lib64/libmsodbcsql-13.0.so.1.0
Database = stockData
Server = cppdatabase.database.windows.net
Port = 1433

And then we connected using the following code:

#include <iostream>
#include <string>
#include <sqlext.h>
#include <sqltypes.h>
#include <sql.h>
#include <stdio.h>
#include <cstdlib>

using namespace std;

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) {  
      retcode = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (void*)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);  

            // Connect to data source  
            retcode = SQLConnect(hdbc, (SQLCHAR*) "mssql", SQL_NTS, (SQLCHAR*) "QuantitateAdmin", 15, "SomeRandomPassword1", 19);  

            // Allocate statement handle  
            if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) {  

                cout << "Success!" << endl;

               retcode = SQLAllocHandle(SQL_HANDLE_STMT, hdbc, &hstmt);   

               // Process data  
               if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO) {  
                  SQLFreeHandle(SQL_HANDLE_STMT, hstmt);  
               }  

               SQLDisconnect(hdbc);  
            } else {
                cout << "Error" << endl;
            }  

            SQLFreeHandle(SQL_HANDLE_DBC, hdbc);  
         }  
      }  
      SQLFreeHandle(SQL_HANDLE_ENV, henv);  
   }  
}