public async Task UpdateAsync(User employee)
        {
            sqlCmd.CommandText = "Update Users set Id=@Id, FirstName=@FirstName where LastName=@LastName;";
            sqlCmd.Connection  = myConnection;
            sqlCmd.Parameters.AddWithValue("@Id", employee.Id);
            sqlCmd.Parameters.AddWithValue("@FirstName", employee.FirstName);
            sqlCmd.Parameters.AddWithValue("@LastName", employee.LastName);

            await SQLExecutor.ExecuteAsync(myConnection, sqlCmd);
        }
        public async Task AddAsync(User user)
        {
            sqlCmd.CommandText = "INSERT INTO Users (Id,FirstName,LastName) Values (@Id,@FirstName,@LastName)";
            sqlCmd.Connection  = myConnection;
            sqlCmd.Parameters.AddWithValue("@Id", user.Id);
            sqlCmd.Parameters.AddWithValue("@FirstName", user.FirstName);
            sqlCmd.Parameters.AddWithValue("@LastName", user.LastName);

            await SQLExecutor.ExecuteAsync(myConnection, sqlCmd);
        }
 public async Task DeleteAsync(int id)
 {
     sqlCmd.Connection  = myConnection;
     sqlCmd.CommandText = "delete from Users where Id=" + id + "";
     await SQLExecutor.ExecuteAsync(myConnection, sqlCmd);
 }