I had an idea of checking if Entry ID already exists in database. If it doesn't there is no point of removing non existing entry.
So when user types then each time new character is added I am opening or closing connection to my database file. This is my concern.
But what if there might be hundredths of entries? Could that cause performance problems? If so, how can I avoid this?
Here is my code:
namespace Password_Manager
{
public partial class DeleteEntryWindow : Form
{
string user, pass, filePath;
// Initializing MainWindow form.
MainWindow mainWindow;
public DeleteEntryWindow()
{
InitializeComponent();
// Creating an EventHandler for textbox when text is chaned.
txtEntryID.TextChanged += new EventHandler(ValidateInput);
}
public DeleteEntryWindow(MainWindow viaParameter,
string user, string pass, string filePath)
: this()
{
mainWindow = viaParameter;
this.user = user;
this.pass = pass;
this.filePath = filePath;
}
private void ValidateInput(object sender, EventArgs e)
{
int intNumber = 0;
// Checking if input is empty, not a number, or is less than 1.
if (!string.IsNullOrEmpty(txtEntryID.Text) &&
int.TryParse(txtEntryID.Text, out intNumber) &&
intNumber > 0)
{
lblMessage.Text = "Entry ID is valid.";
lblMessage.ForeColor = Color.Green;
btnDeleteEntry.Enabled = true;
}
else
{
lblMessage.Text = "You must enter Entry ID number!";
lblMessage.ForeColor = Color.IndianRed;
btnDeleteEntry.Enabled = false;
}
if (!DoesIDExist(intNumber, filePath))
{
lblMessage.Text = "Entry ID doesn't exist!";
lblMessage.ForeColor = Color.IndianRed;
btnDeleteEntry.Enabled = false;
}
}
private void btnDeleteEntry_Click(object sender, EventArgs e)
{
DialogResult result = MessageBox.Show
("Are you sure you want to remove this entry?",
"Information", MessageBoxButtons.YesNo,
MessageBoxIcon.Information);
if (result == DialogResult.Yes)
{
// SQL query which will delete entry by using entry ID.
string sql = "DELETE FROM PersonalData WHERE DataID = " +
txtEntryID.Text;
DeleteData(sql);
lblMessage.Text = "Entry was deleted!";
lblMessage.ForeColor = Color.Green;
}
else
{
// Do nothing.
}
}
private void DeleteData(string sql)
{
HashPhrase hash = new HashPhrase();
string hashShortPass = hash.ShortHash(pass);
// Creating a connection string. Using placeholders make code
// easier to understand.
string connectionString =
@"Provider=Microsoft.ACE.OLEDB.12.0; Data Source={0};
Persist Security Info=False; Jet OLEDB:Database Password={1};";
using (OleDbConnection connection = new OleDbConnection())
{
// Creating command object.
// Using a string formatting let me to insert data into
// place holders I have used earlier.
connection.ConnectionString =
string.Format(connectionString, filePath, hashShortPass);
using (OleDbCommand command = new OleDbCommand(sql, connection))
{
OleDbParameter prmDataID = new OleDbParameter
("@DataID", txtEntryID.Text);
command.Parameters.Add(prmDataID);
try
{
connection.Open();
command.ExecuteNonQuery();
}
catch (Exception ex)
{
MessageBox.Show("Error: " + ex.Message);
}
}
}
// Refreshing state of main window.
mainWindow.DisplayFileContent(filePath);
lblMessage.Text = "Data was successfully deleted.";
lblMessage.ForeColor = Color.Green;
// Clearing text box field.
txtEntryID.Clear();
}
private bool DoesIDExist(int dataID, string filePath)
{
HashPhrase hash = new HashPhrase();
DataTable temp = new DataTable();
string hashShortPass = hash.ShortHash(pass);
bool result = false;
// Creating a connection string. Using placeholders make code
// easier to understand.
string connectionString =
@"Provider=Microsoft.ACE.OLEDB.12.0; Data Source={0};
Persist Security Info=False; Jet OLEDB:Database Password={1};";
string sql = string.Format
("SELECT * FROM PersonalData WHERE [DataID] = {0}", dataID);
using (OleDbConnection connection = new OleDbConnection())
{
// Creating command object.
// Using a string formatting let me to insert data into
// place holders I have used earlier.
connection.ConnectionString =
string.Format(connectionString, filePath, hashShortPass);
using (OleDbCommand command = new OleDbCommand(sql, connection))
{
// Creating command object.
// Using a string formatting let me to insert data into
// place holders I have used earlier.
connection.ConnectionString =
string.Format(connectionString, filePath, hashShortPass);
try
{
// Open database connection.
connection.Open();
using (OleDbDataReader read = command.ExecuteReader())
{
// Checking if there is any data in the file.
if (read.HasRows)
{
// Reading information from the file.
while (read.Read())
{
if (read.GetInt32(0) == dataID)
return true;
}
}
}
}
catch (Exception ex)
{
MessageBox.Show("Error: " + ex.Message);
}
}
}
return result;
}
}
}
