Hi guys ,
I tried to populate QStandardItemModel from Mysql database,but when i view the Tableview only the last low from the database is displayed in the tableview.
where did i go wrong?

Here are the codes related to my problem,
Qt Code: 
  1. customers::customers(QWidget *parent) :
  2.     QWidget(parent),
  3.     m_ui(new Ui::customers)
  4. {
  5.     m_ui->setupUi(this);
  6.     createMainTable();
  7.     populateMainTable();
  8. }
  9. void customers:: createMainTable()
  10. {
  11.  
  13.         model->setHeaderData(0, Qt::Horizontal, QObject::tr("ID"));
  14.         model->setHeaderData(1, Qt::Horizontal, QObject::tr("Name"));
  15.         model->setHeaderData(2, Qt::Horizontal, QObject::tr("First Name"));
  16.         model->setHeaderData(3, Qt::Horizontal, QObject::tr("Category"));
  17.         model->setHeaderData(4, Qt::Horizontal, QObject::tr("Total Amount"));
  18.  
  19.         m_ui->customerView->setModel(model);
  20.         m_ui->customerView->setSelectionBehavior(QAbstractItemView::SelectRows);
  21.         m_ui->customerView->setSelectionMode(QAbstractItemView::SingleSelection);
  22.         m_ui->customerView->setEditTriggers(QAbstractItemView::NoEditTriggers);
  23.  
  24.         m_ui->customerView->setColumnWidth(0, 50);
  25.         m_ui->customerView->setColumnWidth(1, 180);
  26.         m_ui->customerView->setColumnWidth(2, 180);
  27.         m_ui->customerView->setColumnWidth(3, 90);
  28.         m_ui->customerView->setColumnWidth(4, 90);
  29.  
  30.  
  31.         m_ui->customerView->verticalHeader()->hide();
  32.  
  33.       //connect(m_ui->customerView->, SIGNAL(clicked(QModelIndex)), this, SLOT(changeClientInfos(QModelIndex)));
  34.  
  35. }
  36. void customers::populateMainTable() {
  37.  
  39.         model->setHeaderData(0, Qt::Horizontal, QObject::tr("ID"));
  40.         model->setHeaderData(1, Qt::Horizontal, QObject::tr("Name"));
  41.         model->setHeaderData(2, Qt::Horizontal, QObject::tr("First Name"));
  42.         model->setHeaderData(3, Qt::Horizontal, QObject::tr("Category"));
  43.         model->setHeaderData(4, Qt::Horizontal, QObject::tr("Total Amount"));
  44.  
  45.   QSqlQuery query;
  46.   query.exec(QString("SELECT id,LastName, FirstName, Category,Amount FROM customer"));
  47.   while (query.next()) {
  48.  
  49.           db_id =         query.value(0).toString();
  50.           db_LastName =      query.value(1).toString();
  51.           db_FirstName =     query.value(2).toString();
  52.           db_Category =        query.value(3).toString();
  53.           db_Amount =   query.value(4).toString();
  54.  
  55.     }
  56.     int no_cus = query.exec("SELECT COUNT(*) FROM customer");
  57.     for (int i = 0; i < no_cus; i++) {
  58.  
  59.         model->setItem(i, 0, new QStandardItem(db_id));
  60.         model->setItem(i, 1, new QStandardItem(db_LastName));
  61.         model->setItem(i, 2, new QStandardItem(db_FirstName));
  62.         model->setItem(i, 3, new QStandardItem(db_Category));
  63.         model->setItem(i, 4, new QStandardItem(db_Amount));
  64.  
  65.     }
  66.  
  67.     m_ui->customerView->setModel(model);
  68.  
  69.  
  70. }
  71.  
  72. void customers::changeEvent(QEvent *e)
  73. {
  74.     QWidget::changeEvent(e);
  75.     switch (e->type()) {
  76.     case QEvent::LanguageChange:
  77.         m_ui->retranslateUi(this);
  78.         break;
  79.     default:
  80.         break;
  81.     }
  82. }
  83.  
  84. /*  Get data from a form and insert into database */
  85.  
  86. void customers::on_newCustomer_clicked()
  87. {
  88.   dialog = new newCustomer(this);
  89.   int accepted = dialog->exec();
  90.   if(accepted ==  1 )
  91.   {
  92.  
  93.      QList<QString> list = dialog->addCustomer();
  94.  
  95.      QSqlQuery query;
  96.      query.exec("INSERT INTO customer (LastName, FirstName, Category, Amount) VALUES('" + list[0] + "', '" + list[1] + "', '" +list[2] + "', '" +  list[3] + "')");
  97.      populateMainTable();
  98.   }
  99. }
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