using System.Data.SQLite;

private String dbFileName;
        private SQLiteConnection m_dbConn;
        private SQLiteCommand m_sqlCmd;

m_dbConn = new SQLiteConnection();
            m_sqlCmd = new SQLiteCommand();

            dbFileName = textBox1.Text;
            lbStatusText.Text = "Disconnected";
            m_dbConn = new SQLiteConnection("Data Source=" + dbFileName + ";Version=3;");

            try
            {
                m_dbConn.Open();
                lbStatusText.Text = "Connected";
            }
            catch (SQLiteException ex)
            {
                lbStatusText.Text = "Disconnected";
                MessageBox.Show("Error: " + ex.Message);
            }

DataTable dTable = new DataTable();
            String sqlQuery;

            if (m_dbConn.State != ConnectionState.Open)
            {
                MessageBox.Show("Open connection with database");
                return;
            }

            try
            {
                sqlQuery = "SELECT * FROM users";
                SQLiteDataAdapter adapter = new SQLiteDataAdapter(sqlQuery, m_dbConn);
                adapter.Fill(dTable);

                if (dTable.Rows.Count > 0)
                {
                    dgvViewer.Rows.Clear();

                    for (int i = 0; i < dTable.Rows.Count; i++)
                    {
                        dgvViewer.Rows.Add(dTable.Rows[i].ItemArray);
                        MessageBox.Show(dTable.Rows[i].Field('user_id').ToString); //Не работает (непонятно, как получить значение поля в цикле)
                    }
                }
                else
                    MessageBox.Show("Database is empty");
            }
            catch (SQLiteException ex)
            {
                MessageBox.Show("Error: " + ex.Message);
            }