为什么要将空白添加到SQL表的行中?

我不知道这是为什么,基本上,当我使用以下函数插入一行时:

    public bool CreateUser(string username, string password, string email, int age = 0)
    {
        SqlConnection myConnection = new SqlConnection();
        myConnection.ConnectionString = "Data Source=localhost\\SQLEXPRESS;" +
        "Initial Catalog=Pubs;Integrated Security=SSPI;Trusted_Connection=True;";

        try
        {
            myConnection.Open();

            string query = "INSERT INTO SiteUser VALUES('" + username + "', '" +  password + "', '" + email + "', " + age + ")";
            SqlCommand cmd = new SqlCommand(query);
            cmd.Connection = myConnection;
            cmd.ExecuteNonQuery();

            myConnection.Close();
        }
        catch (Exception excep)
        {
            string error = excep.ToString();
            Response.Write(error);

            return false;
        }


        return true;
    }

字段“password”最后会有空格(如“password”)。所以不管密码是什么,后面都是空格。

奇怪的是,“用户名”字段没有发生这种情况,两者都是char(50)类型。