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View data of a database in C# form

I'm new in C# and I don't know how to view data of MySQL in a form. I have already fixed to create a delete button and an add button but now I also want to view that data in the form. I looked up all kinds of things to get it working, but I just can't get it done. Does anyone know what I need to do to get it work?
Here is how I want to view the data: https://i.stack.imgur.com/4Yixa.png
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 MySql.Data.MySqlClient;
namespace Test
{
public partial class Apparatenlijst : Form
{
string MyConnectionString = "Server=localhost;Database=apparatuur;Uid=root;Pwd=;";
public Apparatenlijst()
{
InitializeComponent();
}
private void Apparatenlijst_Load(object sender, EventArgs e)
{
}
private void label2_Click(object sender, EventArgs e)
{
}
private void button1_Click(object sender, EventArgs e)
{
string apparaatt = toevoegg.Text;
MySqlConnection connection = new MySqlConnection(MyConnectionString);
MySqlCommand cmd;
connection.Open();
try
{
cmd = connection.CreateCommand();
cmd.CommandText = "INSERT INTO lijst(apparaatnaam)VALUES(#apparaatnaam)";
cmd.Parameters.AddWithValue("#apparaatnaam", apparaatt);
cmd.ExecuteNonQuery();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
finally
{
if (connection.State == ConnectionState.Open)
{
connection.Close();
MessageBox.Show("Apparaat succesvol toegevoegd");
}
}
}
private void button2_Click(object sender, EventArgs e)
{
}
private void textBox2_TextChanged(object sender, EventArgs e)
{
}
private void verwijder_Click(object sender, EventArgs e)
{
string apparaata = verwijderr.Text;
MySqlConnection connection = new MySqlConnection(MyConnectionString);
MySqlCommand cmd;
connection.Open();
try
{
cmd = connection.CreateCommand();
cmd.CommandText = "DELETE FROM lijst WHERE apparaatnaam=#apparaatnaam";
cmd.Parameters.AddWithValue("#apparaatnaam", apparaata);
cmd.ExecuteNonQuery();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
finally
{
if (connection.State == ConnectionState.Open)
{
connection.Close();
MessageBox.Show("Apparaat succesvol verwijderd");
}
}
}
private void textBox1_TextChanged(object sender, EventArgs e)
{
}
private void lvStudents_SelectedIndexChanged(object sender, EventArgs e)
{
}
}
}

Are you using ListView to display the data?
You can call method MySqlDataAdapter.Fill() to get the datatable from data source. For this, you need to install Nuget package MySql.Data.
Then traverse the datatable and add new ListViewItem object to the ListView.
string constr = #"connection string";
using (MySqlConnection conn = new MySqlConnection(constr))
{
MySqlDataAdapter sda = new MySqlDataAdapter("Select * From lijst", conn);
DataSet ds = new DataSet();
sda.Fill(ds);
listView1.BeginUpdate();
foreach (DataRow row in ds.Tables[0].Rows)
{
ListViewItem lvi = new ListViewItem();
lvi.Text = row["Field1"].ToString();
lvi.SubItems.Add(row["Field2"].ToString());
lvi.SubItems.Add(row["Field3"].ToString());
listView1.Items.Add(lvi);
}
listView1.EndUpdate();
}

C# App - Input string was not in a correct format

I created an app in C# with SQLite Database. When I want to display data from database into a text box, I receive the error: "Input string was not in a correct format".
Here is my code:
public Form1()
{
InitializeComponent();
connectionString = #"Data Source=.\mydb.db;Version =3Integrated Security=True";
}
private void button1_Click(object sender, EventArgs e)
{
using (SQLiteConnection conn = new SQLiteConnection(connectionString))
{
try
{
conn.Open();
if(conn.State == ConnectionState.Open)
{
//MessageBox.Show("Succes!");
SQLiteDataReader reader = null;
SQLiteCommand cmd = new SQLiteCommand("select username from users where id='1'", conn);
reader = cmd.ExecuteReader();
while(reader.Read())
{
textBox1.Text = reader.GetValue(0).ToString();
}
}
conn.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
}

The code from Microsoft's example is like this:
while (reader.Read())
{
Console.WriteLine(String.Format("{0}", reader[0]));
}
So maybe
while(reader.Read())
{
textBox1.Text = reader[0];
}
That said I would be using the debugger to find out more about the element and what you should display.
Just putting it out there but I would be looking and c# MVC or C# Core with entity framework. It's much easier to interact with a database and something I would encourage.

Connection to SQL Server 2008 R2 isn't working

I tried to test if my application is connected to the local database. I don't get any errors, so couldn't quite figure out why it's not working. I only get "no connection" output. I tried to debug it but get connection = null. I have SQL Server 2008 R2 (mixed authentication) and Visual Studio 2008 sp1. I tried connecting using both Windows and SQL Server authentication however neither worked.
This is my web.config file.
<connectionStrings>
<add name="MyDbConn"
connectionString="Data Source=local;Initial Catalog=Sample;Integrated Security=True;"
providerName="System.Data.SqlClient" />
</connectionStrings>
Default.aspx.cs
public partial class _Default: System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void btnTestDb_Click(object sender, EventArgs e)
{
try {
SqlConnection connection = new SqlConnection("Data Source=(local);Initial Catalog=Sample; Integrated Security=SSPI");
connection.Open();
if (connection != null && connection.State == ConnectionState.Closed) {
Response.Write("Connection OK!");
connection.Close();
} else {
Response.Write("No Connection!");
}
} catch {
Response.Write("No Connection!");
}
}
}

//Try this
SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["MyDbConn"].ToString());
protected void btnTestDb_Click(object sender, EventArgs e)
{
try {
con.Open();
if (con.State == ConnectionState.Open)
{
Response.Write("Connection Open");
}
else
{
Response.Write("Connection Closed");
}
con.Close();
} catch {
Response.Write("No Connection!");
}
}

You have some problems in your code that tries to open the connection.
When you try to call connection.Open, the result is an exception if you have problems or simply a connection with its ConnectionState=Open.
Your code instead gives the "Connection OK" message if the ConnectionState is closed, but of course, having just called Open, and if you don't have problems, then the ConnectionState is open.
You could try this code....
protected void btnTestDb_Click(object sender, EventArgs e)
{
string result = TestConnection();
Response.Write(result);
}
private string TestConnection()
{
try
{
using(SqlConnection connection = new SqlConnection("...."))
{
connection.Open();
return "Connection opened correctly";
}
}
catch(Exception ex)
{
return "Error opening the connection:" + ex.Message;
}
}

The written ado.net code will open the connection for sure, but I doubt the connection string will do. Choose appropriate connectionstring from this dedicated site.

how to connect to localhost with this code?

i have a problem with this c# code. I need to connect it to mysql, localhost database, Please give me the correct code to [connetionString = "Data Source=ServerName;Initial Catalog=root;User ID=root;Password="; ] connect to the localhost.
using System;
using System.Windows.Forms;
using System.Data.SqlClient;
namespace WindowsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
string connetionString = null;
SqlConnection cnn ;
**connetionString = "Data Source=ServerName;Initial Catalog=localhost;User ID=root;Password=";**
cnn = new SqlConnection(connetionString);
try
{
cnn.Open();
MessageBox.Show ("Connection Open ! ");
cnn.Close();
}
catch (Exception ex)
{
MessageBox.Show("Can not open connection ! ");
}
}
}
}

It should look a little more like this:
connetionString = "Data Source=localhost;Initial Catalog=<Name of the Database>;User ID=root;Password=";
The data source property is where you put the network location, the initial catalog is the name of the database (in mysql).
Edit:
However, I believe you'll need the mysql libraries, which I notice you're not using at the beginning.
Get them from here: http://dev.mysql.com/downloads/connector/net/
The Data.SqlClient namespace is typically how you'd connect to MSSQL.

it seems you have tagged MySql connection, so preferably you want to use the mysql connection. Which you can download / install here: http://dev.mysql.com/downloads/connector/net/
Also it is wise to use the try-catch-finally approach. So that when the connection opens, and some exception occurs, the connection will always close afterwards.
As another addition, you could put the connectionstring in an App.Config or Web.Config so that you have the connectionstring available in all your files, and only have to adjust it in one place.
hope this will help you
using System;
using System.Windows.Forms;
using MySql.Data.MySqlClient; //using the mysql dll
namespace WindowsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
string connectionString = "Data Source=localhost;Initial Catalog=myDb;User ID=MyUser;Password=MyPass";
MySqlConnection cnn = new MySqlConnection(connectionString);
try
{
cnn.Open();
MessageBox.Show("Connection Open ! ");
}
catch (Exception ex)
{
MessageBox.Show("Can not open connection ! ");
MessageBox.Show(ex.Message); //shows what error actually occurs
}
finally
{
cnn.Close();
}
}
}
}

You are using System.Data.SqlClient in your connection which I think used for SQL Server. Your connection string is also not for MySQL Database. Try this one.
using System.Data.Odbc;
string connectionString = "DRIVER={MySQL ODBC 5.1 Driver}; SERVER=localhost;
DATABASE=dbname; UID=myuserid; PASSWORD=mypassword;OPTION=3; POOLING=false;";
OdbcConnection DBCon = new OdbcConnection(connectionString);
if (DBCon.State == ConnectionState.Open)
{
DBCon.Close();
}
DBCon.Open();
MessageBox.Show ("Connection Open ! ");
DBCon.Close();
Change the ODBC Driver version depending on what you are using.
Change the DATABASE, UID and PASSWORD value.

Here is the code you need
private void btnConnect_Click(object sender, EventArgs e)
{
string MyConStr = "Server=localhost;Database=YourDB;Username=YourUsername;Password=YourPassword";
MySqlConnection conn = new MySqlConnection(MyConStr);
conn.Open();
if (conn.State == ConnectionState.Open)
{
MessageBox.Show("Connection Opened Successfully");
conn.Close();
}
else
{
MessageBox.Show("Error Connecting to DataBase");
}
}

close opened connection using c#

Am using the below code in a class file and access this function for open the connection it return true. I want to close this connection state .I can't do this. please help me to do this.
common.cs
=========
public static bool DBConnectionStatus()
{
try
{
string conString = #"Provider=Microsoft.Jet.OLEDB.4.0; Data Source=|DataDirectory|db_gym.mdb; Jet OLEDB:Database Password=gym_admin";
using (OleDbConnection conn = new OleDbConnection(conString))
{
conn.Open();
return (conn.State == ConnectionState.Open);
}
}
catch (OleDbException)
{
return false;
}
catch (Exception)
{
return false;
}
}
protected void btn_general_Click(object sender, EventArgs e)
{
try
{
bool state = common.DBConnectionStatus();
if(state == true)
{
// Some operation
}
// I want to close this connection
}
catch (Exception e1)
{
}
}

A using statement is translated into three parts: acquisition, usage, and disposal.
using (OleDbConnection conn = new OleDbConnection(conString))
{
conn.Open();
return (conn.State == ConnectionState.Open);
//connection is automatically closed and disposed here
}
More information at MSDN article.

You better give back an open connection because you need that in an OleDbCommand. You coukd hide the connection as well in the Common class if you like but if you keep it in the using statement there is no open connection when you get status so basically if true is returned your connection in reality is closed (and Disposed). Refactor to something like this:
public OleDbConnection GetOpenConnection()
{
string conString = #"Provider=Microsoft.Jet.OLEDB.4.0; Data Source=|DataDirectory|db_gym.mdb; Jet OLEDB:Database Password=gym_admin";
OleDbConnection conn = new OleDbConnection(conString))
conn.Open();
return conn;
}
protected void btn_general_Click(object sender, EventArgs e)
{
try
{
using(OleDbConnection openConnection = common.GetOpenConnection())
{
// I want to close this connection
openConnection.Close(); // close asap
} // dispose
}
catch (Exception e1)
{
}
}