Пересматриваем решение на счёт SQL

src/database/database.qbs

@@ -0,0 +1,16 @@
+import qbs
+
+PSLibrary {
+    Depends { name: "Qt"; submodules: "sql"}
+
+    Depends { name: "model" }
+    Depends { name: "sql_builder" }
+
+    Group {
+        name: "cpp"
+        files: [
+            "**/*.h",
+            "**/*.cpp"
+        ]
+    }
+}

src/database/databasemanager.cpp

@@ -0,0 +1,38 @@
+#include "databasemanager.h"
+
+#include <model/author.h>
+#include <model/book.h>
+
+DatabaseManager::DatabaseManager() {}
+
+DatabaseManager::~DatabaseManager()
+{
+    if (db.isOpen())
+        db.close();
+}
+
+DatabaseManager& DatabaseManager::instance()
+{
+    static DatabaseManager instance;
+    return instance;
+}
+
+bool DatabaseManager::connect(const QString& dbPath)
+{
+    db = QSqlDatabase::addDatabase("QSQLITE");
+    db.setDatabaseName(dbPath);
+    return db.open();
+}
+
+QSqlDatabase& DatabaseManager::database()
+{
+    return db;
+}
+
+void DatabaseManager::initializeDatabase()
+{
+    QSqlQuery query;
+
+    query.exec(model::createTableBook());
+    query.exec(model::createTableAuthor());
+}

src/database/databasemanager.h

@@ -0,0 +1,21 @@
+#ifndef DATABASEMANAGER_H
+#define DATABASEMANAGER_H
+
+#include <QDebug>
+#include <QtSql>
+
+class Q_DECL_EXPORT DatabaseManager
+{
+public:
+    static DatabaseManager& instance();
+    bool connect(const QString& dbPath);
+    QSqlDatabase& database();
+    void initializeDatabase();
+
+private:
+    DatabaseManager();
+    ~DatabaseManager();
+    QSqlDatabase db;
+};
+
+#endif // DATABASEMANAGER_H