Add SQLHelper and CenterAlignSqlTableModel. The CenterAlignSqlTableModel only make the cell text align center.

src/db/SQLHelper.h

@@ -0,0 +1,25 @@
+//
+// Created by Krad on 2021/10/11.
+//
+
+#ifndef GUI_SQLHELPER_H
+#define GUI_SQLHELPER_H
+
+class QSqlDatabase;
+#include "CenterAlignSqlTableModel.h"
+#include <QString>
+#include <QHash>
+
+class SQLHelper {
+public:
+    static bool Open();
+    static bool Open(QSqlDatabase* base);
+    static void Close();
+    static QSqlTableModel* getTable(const QString & tableName);
+private:
+    static QSqlDatabase*  defaultDatabase;
+    static QHash<QString,CenterAlignSqlTableModel*>* cache;
+};
+
+
+#endif //GUI_SQLHELPER_H