QSqlQuery query statement limit? Can't delete from table when the query statement is very long (Sqlite)

[hbatalha]

@Christian-Ehrlicher @jsulm @JonB @SGaist @KroMignon

I think I solved the problem! When I was inserting that obscured CHAR, the type I was using was QByteArray and when trying to delete the type was a QString. Even though they contained the same characters something I don't know what yet was stopping it from getting deleted.

.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QtSql>

QT_BEGIN_NAMESPACE
namespace Ui {
class MainWindow;
}
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private slots:
    void on_add_clicked();

    void on_delete_2_clicked();

private:
    Ui::MainWindow *ui;

    QSqlDatabase d_base;
};
#endif // MAINWINDOW_H

.cpp

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    d_base = QSqlDatabase::addDatabase("QSQLITE");
    d_base.setDatabaseName("database.sqlite");

    if(!d_base.open())
    {
        qDebug() << "Database failed to open : " + d_base.lastError().text();
    }

    QSqlQuery query;

    bool success = false;

    success = query.exec("CREATE TABLE IF NOT EXISTS mytable("
                         "attribute CHAR NOT NULL PRIMARY KEY)");

    if(! success)
    {
        qDebug() << "SQL QUERY ERROR: " <<  query.lastError().text();
    }
}

MainWindow::~MainWindow()
{
    delete ui;
}


void MainWindow::on_add_clicked()
{
    if( ! ui->lineEdit->text().isEmpty())
    {
        QSqlQuery query;

        query.prepare("INSERT INTO mytable (attribute) VALUES(:attribute)");

        QByteArray obscuredStr = ui->lineEdit->text().toUtf8();
        obscuredStr = obscuredStr.toBase64();
        QString str = obscuredStr;
        qDebug() << str;
        query.bindValue(":attribute", str);

        if( ! query.exec())
        {
            qDebug() << "SQL QUERY ERROR: " + query.lastError().text();
        }
    }
}


void MainWindow::on_delete_2_clicked()
{
    QSqlQuery query;

    QByteArray obscuredStr = ui->lineEdit->text().toUtf8();
    obscuredStr = obscuredStr.toBase64();
    qDebug() << obscuredStr;

    QString strt = obscuredStr;
    qDebug() << strt;
    if( ! query.exec("DELETE FROM mytable WHERE attribute = '" + strt + "'" ))
    {
        qDebug() << "SQL QUERY ERROR:" <<  query.lastError().text();
    }
}

.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>305</width>
    <height>161</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <widget class="QPushButton" name="add">
    <property name="geometry">
     <rect>
      <x>10</x>
      <y>70</y>
      <width>121</width>
      <height>25</height>
     </rect>
    </property>
    <property name="text">
     <string>Add to table</string>
    </property>
   </widget>
   <widget class="QPushButton" name="delete_2">
    <property name="geometry">
     <rect>
      <x>150</x>
      <y>70</y>
      <width>121</width>
      <height>25</height>
     </rect>
    </property>
    <property name="text">
     <string>Delete from table</string>
    </property>
   </widget>
   <widget class="QLineEdit" name="lineEdit">
    <property name="geometry">
     <rect>
      <x>10</x>
      <y>40</y>
      <width>261</width>
      <height>24</height>
     </rect>
    </property>
   </widget>
  </widget>
  <widget class="QMenuBar" name="menubar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>305</width>
     <height>25</height>
    </rect>
   </property>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
 </widget>
 <resources/>
 <connections/>
</ui>

I also noticed from the example above that whenever I insert data into the table using a QByteArray object and then trying to delete the row of that data using the column that contains it nothing happens, no deletion and also and no error is thrown.

Thank you all for helping me debug!!