public Management(string path)
        {
            SQLiteConnection connection = null;

            try
            {
                connection = ConnectionsKeeper.getConnection(path);
            }
            catch (Exception ex1)
            {
                try
                {
                    CreateDB(path);
                }
                catch (Exception ex2)
                {
                    throw new Exception("No data base and can not to create it: " + path);
                }
                connection = ConnectionsKeeper.getConnection(path);
            }
        }
 public SubjectsListManager(String dbPath)
 {
     connection = ConnectionsKeeper.getConnection(dbPath);
 }
 public LessonsListManager(String dbPath)
 {
     connection  = ConnectionsKeeper.getConnection(dbPath);
     this.dbPath = dbPath;
 }