I am learning C# along with Visual Studio 2013. I finally was able to get all the errors cleared. But when my form comes up the data grid is empty. Even if I put in a search for a certain ID I get nothing.
Here is my code: There is not a code block or am I in the wrong place?
using System;using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.SQLite;
namespace StudentDB1
{
public partial class Form1 : Form
{
private String connectionString;
private SQLiteConnection connection;
private String SQLInsert = "INSERT INTO User(LastName, FirstName, StuID, Grade, Address, City, State, Zip, Phone, ParentName) VALUES(?, ?)";
private String SQLUpdate = "UPDATE User SET LastName = ?, FirstName = ?, StuID = ?, Grade = ?, Address = ?, City = ?, State = ?, Zip = ?, Phone = ?, ParentName = ? where UserId = ?";
private String SQLSelect = "SELECT * FROM User";
private String SQLDelete = "DELETE FROM User WHERE UserId = ?";
public Form1()
{
InitializeComponent();
connectionString = System.Configuration.ConfigurationManager.ConnectionStrings["dbconnection"].ConnectionString;
connection = new SQLiteConnection(connectionString);
}
private void textBox10_TextChanged(object sender, EventArgs e)
{
}
private void btnSelect_Click(object sender, EventArgs e)
{
}
private void btnExit_Click(object sender, EventArgs e)
{
if (connection.State == ConnectionState.Open)
connection.Close();
Application.Exit();
}
private void btnSave_Click(object sender, EventArgs e)
{
if (String.IsNullOrEmpty(txtStuId.Text))
{
if (connection.State != ConnectionState.Open)
connection.Open();
SQLiteCommand command = connection.CreateCommand();
command.CommandText = SQLInsert;
command.Parameters.AddWithValue("FirstName", txtFirstName.Text);
command.Parameters.AddWithValue("LastName", txtLastName.Text);
command.ExecuteNonQuery();
connection.Close();
}
else
{
if (connection.State != ConnectionState.Open)
connection.Open();
SQLiteCommand command = connection.CreateCommand();
command.CommandText = SQLUpdate;
command.Parameters.AddWithValue("FirstName", txtFirstName.Text);
command.Parameters.AddWithValue("LastName", txtLastName.Text);
command.Parameters.AddWithValue("UserId", int.Parse(txtStuId.Text));
command.ExecuteNonQuery();
connection.Close();
clean();
search();
}
}
private void clean()
{
txtStuId.Text = String.Empty;
txtFirstName.Text = String.Empty;
txtLastName.Text = String.Empty;
txtStuId.Text = String.Empty;
txtGrade.Text = String.Empty;
txtAddress.Text = String.Empty;
txtCity.Text = String.Empty;
txtState.Text = String.Empty;
txtZip.Text = String.Empty;
txtPhone.Text = String.Empty;
txtParentName.Text = String.Empty;
}
private void search()
{
// Eliminamos el handler del evento RowEnter para evitar que se dispare al
// realizar la búsqueda
dataGrid.RowEnter -= dataGrid_RowEnter;
// Abrimos la conexión
if (connection.State != ConnectionState.Open)
connection.Open();
// Creamos un SQLiteCommand y le asignamos la cadena de consulta
SQLiteCommand command = connection.CreateCommand();
command.CommandText = SQLSelect;
// Creamos un nuevo DataTable y un DataAdapter a partir de la SELECT.
// A continuación, rellenamos la tabla con el DataAdapter
DataTable dt = new DataTable();
SQLiteDataAdapter da = new SQLiteDataAdapter(command);
da.Fill(dt);
// Asignamos el DataTable al DataGrid y cerramos la conexión
dataGrid.DataSource = dt;
connection.Close();
// Restauramos el handler del evento
dataGrid.RowEnter += dataGrid_RowEnter;
}
private void dataGrid_RowEnter(object sender, DataGridViewCellEventArgs e)
{
// Recuperamos ID, nombre y apellido de la fila
int id = int.Parse(dataGrid.Rows[e.RowIndex].Cells[0].Value.ToString());
String name = (String)dataGrid.Rows[e.RowIndex].Cells[1].Value;
String surname = (String)dataGrid.Rows[e.RowIndex].Cells[2].Value;
// Asignamos los valores a las cajas de texto
txtStuId.Text = id.ToString();
txtFirstName.Text = name;
txtLastName.Text = surname;
}
private void Form1_Load(object sender, EventArgs e)
{
}
private void dataGrid_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
}
private void txtId_TextChanged(object sender, EventArgs e)
{
}
private void txtName_TextChanged(object sender, EventArgs e)
{
}
}
}