/* the Query function is a dynamic query processor. It requires two arguments: an ODBC data source name (DSN) and an SQL Query statement. The query result is printed out on the screen.  The DSN can also be a connect string in a format of DSN=DataSourceName;UID=YourUserId;PWD=YourPassword*/

long Query(const char * szDataSource, const char * szSQL)
{
    int nTotalRows=0;
    Broker *pBroker =CreateBroker(Broker::DATA_BROKER, NULL);

    // make a database connection , without user name and pwd
    if(!pBroker->Connect(szDataSource, "", ""))
    {
        // we have trouble connecting to the database
        printf("Unable to connect to the database %s\n",
            szDataSource);
        return 0;
    }

    if(pBroker->OpenSQL(szSQL))
    {
        printf("%s\n", pBroker->GetHeader());
        long rows=0;
        while((rows=pBroker->Fetch())>0)
        {
            // we fetched n rows each time.
            for(int i=0; i<rows; i++)
            {   // print out each record.
                printf("%s\n", pBroker->GetRecord(i));
            }
            nTotalRows +=rows;
        }
    }
    else
    {
        // some thing wrong, get the error string
        printf("Error open query, %s\n",
            pBroker->GetErrorString());
    }
    // we are done
    DestroyBroker(pBroker);
    return nTotalRows;
}

// this is a little test program for our Query function.
main(int argc, char **argv)
{
    char szSQL[500];
    if(argc!=2)
    {   // assume our name is query.exe.
        printf("Usage: query.exe DataSource\n");
    }

    while(1)
    {
        printf("Type in your sql statement.\n");
        gets(szSQL);
        int nRows=Query(argv[1], szSQL);
        printf("\n %d rows returned.\n", nRows);
    }
    return 0;
}




Special Note:

	Exception handling is omitted for simplicity.
	The Query function makes a database connection whenever it processes a query statement. This could be time consuming. A better way is to have the broker connected to the database only once, and use the same connection for all the SQL statements. This can be done if the Broker is created in the main function and move the database connection from ExecuteSQL to main().