Load a new Sqlite database problem

[ChrisW67]

You cannot use the QSqlQuery to pass data back to other parts of the program if you insist on closing the database connection (even if it let you). It probably won't let you close the database connection because the QSqlQuery you create and execute is still active.

Why do you want to keep opening and closing the connection rather than keeping a persistent connection for the life of your sql_functions instance?

How about something like (untested - not at my machine):

#include "sql_functions.hpp"
 
sql_functions::sql_functions( const QString database ):
    m_database(database)
{
  // Establish the database connection
  QSQLDatabase db = QSqlDatabase::addDatabase( "QSQLITE" );
  db.setDatabaseName( m_database );
  db.open();
 
   /**
    * Create structure :
    *    - to store data for SQL request
    *    - to store data for statistics
    **/
   s_req   = new Struct_Request;
   s_stats = new Struct_Statistic;
}
 
sql_functions::~sql_functions()
{
   delete s_req;
   delete s_stats;
 
   QString connectionName;
   {  // scope the db instance so that removeDatabase does not complain
       // about active connections.
     QSqlDatabase db = QSqlDatabase::database();
     connectionname = db.connectionName();
     if (db.isOpen())
       db.close();
   }
   QSqlDatabase::removeDatabase(connectionName);
 
}
 
void sql_functions::exec( const int request_type, QString movie_title, 
                                   QString type,  QString borrower_name,
                          QString Id_movie_update )
{
   /** Clear data field in request structure **/
   s_req->data.clear();
 
   QSqlDatabase db = QSqlDatabase::database();
 
   /** If no error occured, SQL request is executed **/
   if ( db.open() )
   {      
      s_req->data = QSqlQuery( db );
      switch( request_type )
      {
         case RequestSQL::DISPLAY_ALL :
            s_req->data.exec( "SELECT type,titre,dvd_en_pret,bluray_en_pret,dvd_prete_a,bluray_prete_a,est_combo "
                              "FROM films ORDER BY titre COLLATE NOCASE;" );
            break;
 
         case RequestSQL::DISPLAY_DVD :
            s_req->data.exec( "SELECT type,titre,dvd_en_pret,bluray_en_pret,dvd_prete_a,bluray_prete_a,est_combo
                              "FROM films WHERE type IN ('DVD') ORDER BY titre COLLATE NOCASE;" );
            break;
 
         case RequestSQL::DISPLAY_BLURAY :
            s_req->data.exec( "SELECT type,titre,dvd_en_pret,bluray_en_pret,dvd_prete_a,bluray_prete_a,est_combo "
                              "FROM films WHERE type IN ('BLURAY') ORDER BY titre COLLATE NOCASE;" );
            break;
 
         default:
            break;
      }
 
   }
}

#include "sql_functions.hpp"

sql_functions::sql_functions( const QString database ):
    m_database(database)
{
  // Establish the database connection
  QSQLDatabase db = QSqlDatabase::addDatabase( "QSQLITE" );
  db.setDatabaseName( m_database );
  db.open();

   /**
    * Create structure :
    *    - to store data for SQL request
    *    - to store data for statistics
    **/
   s_req   = new Struct_Request;
   s_stats = new Struct_Statistic;
}

sql_functions::~sql_functions()
{
   delete s_req;
   delete s_stats;

   QString connectionName;
   {  // scope the db instance so that removeDatabase does not complain
       // about active connections.
     QSqlDatabase db = QSqlDatabase::database();
     connectionname = db.connectionName();
     if (db.isOpen())
       db.close();
   }
   QSqlDatabase::removeDatabase(connectionName);

}

void sql_functions::exec( const int request_type, QString movie_title, 
                                   QString type,  QString borrower_name,
                          QString Id_movie_update )
{
   /** Clear data field in request structure **/
   s_req->data.clear();

   QSqlDatabase db = QSqlDatabase::database();

   /** If no error occured, SQL request is executed **/
   if ( db.open() )
   {      
      s_req->data = QSqlQuery( db );
      switch( request_type )
      {
         case RequestSQL::DISPLAY_ALL :
            s_req->data.exec( "SELECT type,titre,dvd_en_pret,bluray_en_pret,dvd_prete_a,bluray_prete_a,est_combo "
                              "FROM films ORDER BY titre COLLATE NOCASE;" );
            break;

         case RequestSQL::DISPLAY_DVD :
            s_req->data.exec( "SELECT type,titre,dvd_en_pret,bluray_en_pret,dvd_prete_a,bluray_prete_a,est_combo
                              "FROM films WHERE type IN ('DVD') ORDER BY titre COLLATE NOCASE;" );
            break;

         case RequestSQL::DISPLAY_BLURAY :
            s_req->data.exec( "SELECT type,titre,dvd_en_pret,bluray_en_pret,dvd_prete_a,bluray_prete_a,est_combo "
                              "FROM films WHERE type IN ('BLURAY') ORDER BY titre COLLATE NOCASE;" );
            break;

         default:
            break;
      }

   }
}

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no m_db, no first_call, no constant open/close.

[beware]

Thanks for your answer. I update my code.

No compilation problem, but i have an error when i closing my program, here :

QSqlDatabasePrivate::removeDatabase: connection 'qt_sql_default_connection' is still in use, all queries will cease to work.

QSqlDatabasePrivate::removeDatabase: connection 'qt_sql_default_connection' is still in use, all queries will cease to work.

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[ChrisW67]

Where else are you creating queries against the database? Are you creating copies of the query created by this class elsewhere in the program? Are they being cleared or deleted before this point?

[beware]

Well,
All my SQL querries are create in function

void sql_functions::exec

void sql_functions::exec

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Querries result are store in a structure, and others function can used this value to get back request values with

QString result;
while s_req->data.next()
     result = s_req->data.value(0).toString();

QString result;
while s_req->data.next()
     result = s_req->data.value(0).toString();

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I only clear the querry in the begining of the function.