Return "SELECT" sql command

Question

I am trying to make my form contain all the rows of a table of a Postgres database, for this I am using a DataGridView with 2 columns (name and password), and searching the database for the values. But I'm new to this, and i don't know how to take db data and put it in the DataGrid.

Basically I wanted to make the same pgAdmin visual table be shown in my C# application form.

Postgre.cs:

public static NpgsqlDataReader listUsers()
        {
            string sqlCommand = "SELECT name, senha FROM users";
            NpgsqlCommand cmd = new NpgsqlCommand(sqlCommand, Connect());

            NpgsqlDataReader reader = cmd.ExecuteReader();

            return reader;
        }

frmAdmin:

public partial class frmAdmin : Form
    {
        public frmAdmin()
        {
            dataGridView1.DataSource = Postgre.listUsers();
            InitializeComponent();
        }
    }

I took part of the code from here

I think it should work, but when I run I get a System.StackOverflowException.

Edit1: I solved the overflow problem, but now the problem is "System.NullReferenceException", in the dataGridView1.DataSource = Postgre.listUsers(). I updated the code.

Answer 1

try it:

dataGridView1.DataSource = reader;