[odb-users] How to run a select query to a DB from C++?

[Visa Karthick]

I am troubleshooting a program and need some assistance. Below is the code.

void initialiseDB(std::unique_ptr<odb::database>& db) {
    try
    {
        odb::transaction t2(db->begin());
        // Find function should be invoked here
        auto tankType = std::make_shared<EntityType>("Tank");
        db->persist(tankType.get()); // This inserts a new record with value Tank in the   EntityType table.
        t2.commit();
    }
    catch (const odb::exception &e)
    {
        std::cerr << e.what() << std::endl;
        return;
    }
    }


The above code works fine for inserting records in to a Sqlite table. The problem is it keeps adding the same row again and again When I run the program. I need to insert records only when the table is empty. There is another function for running a select query in the database. It is invoked by the below code.

template <typename T>
     inline typename object_traits<T>::pointer_type database::
     find (const typename object_traits<T>::id_type& id)
     {
     return find_<T, id_common> (id);
     }

     template <typename T>
  inline bool database::
  find (const typename object_traits<T>::id_type& id, T& obj)
  {
    return find_<T, id_common> (id, obj);
  }


I need to invoke the find function first, and only if it doesnt return any result persist function should be called. I am unsure what parameters to be passed from my current scope. Could you please advise?

I am not sure what parameters to be passed.



Visa Karthick  | Electrical Engineer | Victoria

IRIS Integration Pty Ltd

T:+61 1300 240 036 | M : +61 405918505 | visa.karthick at IRISI.com.au<mailto:visa.karthick at IRISI.com.au>