im working in WinForms C#.
for some reason when I want to populate my listBox it stops and says my database is corrupt.
I have added a repair line and the codes run afterwards, but nothing happends. My listbox is not populated.
Here is the code im using.:
public void button1_Click(object sender, EventArgs e)
{
SqlCeConnection cn = new SqlCeConnection(#"Data Source = Database1.mdf");
cn.Open();
SqlCeCommand cm = new SqlCeCommand("SELECT * FROM tblprojects ORDER BY Projekt_liste ASC", cn);
try
{
SqlCeDataReader dr = cm.ExecuteReader();
while (dr.Read())
{
ListBox project_list = Application.OpenForms["Form1"].Controls["tabControl1"].Controls["tabPage1"].Controls["Project_list"] as ListBox;
project_list.Items.Add(dr["Projekt_liste"].ToString());
}
cn.Close();
cn.Dispose();
}
catch (Exception ex)
{
}
}
public void button2_Click(object sender, EventArgs e)
{
SqlCeConnection cn = new SqlCeConnection();
SqlCeEngine engine = new SqlCeEngine("Data Source = Database1.mdf");
if (false == engine.Verify())
{
MessageBox.Show("Database is corrupted.");
engine.Repair(null, RepairOption.RecoverAllPossibleRows);
}
}
For example if you want to load the items
1. make sure you have a ListBox on the winform
2. name the ListBox
3. Create a ListItem
4 Add the ListItem to the ListBox
while(dr.Read())
{
ListViewItem obj=new ListViewItem(Convert.ToString(dr[0]),Convert.ToString(dr[1]);
//in object of ListViewItem give display member at first and give value member at second position
listView1.Items.Add(obj); // add object to the listbox
}
Here are a few links that you can use as well to show different ways on how to populate a ListBox
one is Windows and the other will be if you are using or plan to use ASP.NET
Populate a ListBox when using SQLDataReader
asp.net SqlDataReader example: how to use Read() method to populate ListBox
Populate ASP.NET ListBox using SqlDataReader
From Microsoft Site
The Repair method does not guarantee complete data recovery for every
database. Some forms of data corruptions cannot be repaired
completely, regardless of the Repair option that is selected by the
application.
This could be one of the case where your file is corrupted.
Also please try To have repair call straight above the call to populate Data in List.
This may help.
Related
Using C# and Winform.
I read a couple of similar questions but couldn't find any great answers that could interlock with my code. So, bear with me and thank you in advance for helping me.
I have a single form that contains multiple User Controls. Inside the first user control, you can insert, update and delete records from the database. In the second User Control, there is a datagridview that is populated with all records.
The problem I have is that whenever I insert, update or delete a record inside the first user control. It won't refresh inside the datagridview when I swap to the second user control.
Beneath is the second user control that populates the datagridview
private void populate()
{
database.OpenConnection();
string query = "SELECT id, name, qoute, time, date from maintable";
SQLiteDataAdapter sda = new SQLiteDataAdapter(query, database.connection);
SQLiteCommandBuilder builder = new SQLiteCommandBuilder(sda);
var ds = new DataSet();
sda.Fill(ds);
dtgNav.DataSource = ds.Tables[0];
databas.CloseConnection();
}
private void Navigation_Load(object sender, EventArgs e)
{
populate();
dtgNav.Columns[0].HeaderText = "ID";
}
public void Refresh()
{
this.Refresh();
}
Beneath is the code for adding a record to the datagridview in the first user control
private void btnAdd_Click(object sender, EventArgs e)
{
database.OpenConnection();
string query = "INSERT INTO maintable (`id`, `name`, `qoute`, `time`,`date`) VALUES (#Id, #Name, #Qoute, #Time, #Date)";
SQLiteCommand command = new SQLiteCommand(query, database.connection);
command.Parameters.AddWithValue("#Id", tbxID.Text);
command.Parameters.AddWithValue("#Name", tbxName.Text.Trim());
command.Parameters.AddWithValue("#Qoute", tbxQoute.Text.Trim());
command.Parameters.AddWithValue("#Time", tbxTime.Text.Trim());
command.Parameters.AddWithValue("#Date", dtpDate.Value.ToString("yyyy-MM-dd"));
command.ExecuteNonQuery();
MessageBox.Show("Added new event into the database.");
database.CloseConnection();
usercontrol2.Refresh();
}
I would appreciate it if we found a way to refresh the datagridview when the button is clicked without changing the original code all too much.
You have a public void Refresh method in the second usercontrol, try modifying this.Refresh();, to say populate();. this should call your private void populate method that you called when loading which should reload the grid. Let me know if this helps.
I am creating a program that will provide a front end to open files from server locations without having to navigate to server locations. The program has buttons that open lists for certain categories, then a single button to open the file from the currently selected item from the list.
My current issue is being able to identify which ListBox is currently in view, so that the program knows which list to use as a reference to open the right file.
Is there a way to create an "object" called "List", then assign the listbox to it and reference it? It does not seem to like what I have done.
object ListBox;
int IdCheck = 0;
string DriveLoc;
private void ButtAirInfo_Click(object sender, EventArgs e)
{
GBAirInfo.Visible = true;
GBAir.Visible = false;
ListBox = LBAirInfo; //Here is where I load the List on to the screen, then
//assign the list to the object ListBox
}
private void button2_Click(object sender, EventArgs e)
{
using (connection = new SqlConnection(connectionString))
using (SqlDataAdapter adapter = new SqlDataAdapter("SELECT * FROM Files", connection))
{
DataTable FilesTable = new DataTable();
adapter.Fill(FilesTable);
if (ListBox.SelectedIndex == -1)
MessageBox.Show("No Items selected");
else
IdCheck = ListBox.SelectedIndex;
DriveLoc = (FilesTable.Rows[IdCheck]["Location"].ToString());
if (DriveLoc == "")
MessageBox.Show("Item does not have a location");
else
System.Diagnostics.Process.Start(#DriveLoc);
}
Ok, so my own research has found that you can assign a listbox to a generic term using -
Listbox ListBx
this.ListBx = Listbox1;
This way, I can ensure one piece of code will work for all Listboxes, and all I need to do is change the Listbox assigned to ListBx when I load each List through buttons. I hope this helps someone downt he line.
private void button1_Click(object sender, EventArgs e)
{
using (SqlConnection connection = new SqlConnection(ConnectionString)
{
connection.Open();
SqlCommand cmd = new SqlCommand("update dictionary set word=#word", connection);
cmd.Parameters.AddWithValue("#word", wordTextBox.Text);
cmd.ExecuteNonQuery();
this.Close();
}
}
I created a way to take a selected value in a listbox and add the item to a text box on a seperate form. There I am attempting to give the user a way to change that word and have it reflected in the dataset I created. Currently when I change that word it replaces every entry in my dataset with the new word as opposed to just the specific entry. I am trying to figure how to specify just to change that one item.
That is because you are missing a WHERE clause in your query. You need to use a WHERE clause in your query to only update some selected records that you like :
eg : update dictionary set word=#word WHERE ID=#ID.
This is just an example. You have to put the WHERE clause as per your requirement.
Hope this helps.
I have two dropdownlists, ddlstates and ddlcitys.
The ddlstates has a list of Brazilian states that when clicked, loads the ddlcitys with the cities of that state. Until then, everything works correctly, but when clicking the save button which makes verification of completed fields or not, the ddlcitys back to the first option. How to store the information ddlcitys before the postback?
In code behind, have code that loads the ddlcitys:
protected void ddlstates_TextChanged(object sender, EventArgs e)
{
if (ddlstates.Text != "")
{
List<ListItem> cidades = new List<ListItem>();
SqlConnection conn = new SqlConnection(mytools.stringconection);
SqlDataReader dr = null;
conn.Open();
SqlCommand cmd = new SqlCommand("select ciddesc from cidades where cidestsigla = '" + ddlstates.SelectedValue.ToString() + "' order by 1 asc");
cmd.Connection = conn;
dr = cmd.ExecuteReader();
ddlcitys.Items.Clear();
while (dr.Read())
{
cidades.Add(new ListItem(dr[0].ToString()));
}
dr.Close();
conn.Close();
ddlcitys.DataTextField = "Text";
ddlcitys.DataValueField = "Value";
ddlcitys.DataSource = cidades;
ddlcitys.DataBind();
}
}
Asked long time ago, anyway may the answer help anyone.
On your page load event before bind any of your dropdownlists, make sure that not post back, then on your dropdown select change events , your dropdown values will not re bind so values will not changed.
hint : make sure that your aspx page enable view state (by default enabled) read more.
protected void Page_Load(object sender, EventArgs e) {
if (!IsPostBack) {
//this will called when your page loaded at first time, so bind your drop down values here.
} else {
//this will called on select change, don't bind your dropdown again, then values will be same (asp.net web forms viewstates will handle read more about viewstate).
}
}
So I've got a class, commenter, and two methods within that class, SaveBtn_Click - created primarily not by me, and then also PeerReview, primarily created by me.
Anyway, the code starts off like this (after a variety of using statements):
public partial class commenter : System.Web.UI.Page
{
string employee_reviewed;
PeerReview pr = new PeerReview();
public void SaveBtn_Click(object sender, EventArgs e)
{
//all the information for the SaveBtn_Click method.
}
After that, I have PeerReview:
public void PeerReview(System.Web.UI.WebControls.ListBox listbox)
{
MySqlConnection con = new MySqlConnection("server=localhost;database=hourtracking;uid=username;password=password");
MySqlCommand cmd = new MySqlCommand("select first_name from employee where active_status=1", con);
con.Open();
MySqlDataReader r = cmd.ExecuteReader();
Console.WriteLine("Another test!");
Console.WriteLine(r);
Console.WriteLine("Hi, this is a test!");
while (r.Read())
{
listbox.Items.Add(new ListItem(Convert.ToString(r["first_name"]), Convert.ToString(r["first_name"])));
}
con.Close();
}
I'm connecting this with ASP.NET, and I can get the listbox to show up, but not the individual items in the listbox. I'm testing it with a console.writeline command, to see if that outputs anything - but nothing is being put out on the ASP page.
I'm not certain how I should reference these particular sections (new to C#, asking like 3 dozen questions about this).
ASP code looks like this:
<asp:ListBox ID="listBox1" runat="server">
You have some confused declarations.
You declare a method called PeerReview, but you also have an attempt to create an instance of PeerReview as though it were a type. I think you really just want to call the PeerReview method from your button click event, eg
public void SaveBtn_Click(object sender, EventArgs e)
{
PeerReview();
}
And then eliminate the "PeerReview pr = new PeerReview();" line. Also, as this is on a page, you have an implicit reference within the partial class to the listbox by its ID, so you don't need to pass it as a parameter. And the Console.WriteLines are not useful in a web application - you might try Response.Write if you're wanting to add that to the output for debug purposes.
Edits based on OP response
You should call PeerReview in the Page_Load event handler:
public void Page_Load(object sender, EventArgs e)
{
// You need to determine if you should call PeerReview every time the page
// loads, or only on the initial call of the page, thus determining whether
// you need the IsPostBack() test. My instinct is that you *do* want to constrain
// it to the first pass, but only you can make that determination for
// certain based on your requirements.
if (!Page.IsPostBack) //Do you need this check?
{
PeerReview();
}
}
You're trying to add items to listbox though your listBox has an id of listBox1
Rather than looping through your data and adding items why not bind the datasource to your listbox and then set the DataTextField and DataValueField on your listbox.
So for example (typos may exist..sorry.. been a while since i wrote C#)
MySqlConnection con = new MySqlConnection("server=localhost;database=hourtracking;uid=username;password=password");
MySqlCommand cmd = new MySqlCommand("select first_name from employee where active_status=1", con);
con.Open();
MySqlDataReader r = cmd.ExecuteReader();
listBox1.DataSource = r;
listBox1.DataBind();
con.Close();
If you can't bind to the reader (can't remember..) then dump your results into a datatable first, then bind to the listBox1
DataTable dTable = New DataTable();
dTable.Load(reader);
listBox1.DataSource = dTable;
listBox1.DataBind();
in your asp, set the listBox fields like:
<asp:ListBox ID="listBox1" runat="server" DataTextField="first_name" DataValueField="first_name">
quick view here is you are adding items to listbox instead of listBox1
change:
listbox.Items.Add(new ListItem(Convert.ToString(r["first_name"]), Convert.ToString(r["first_name"])));
to:
listBox1.Items.Add(new ListItem(Convert.ToString(r["first_name"]), Convert.ToString(r["first_name"])));