Develop Reference

How to fix input string was not in a correct format in sql on C#?

public static String AccountNumber;
public static double oldBalance, newBalance;
SqlConnection connection = new SqlConnection(#"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=D:\CSharp\ATM\DB\LoginDB.mdf;Integrated Security=True;Connect Timeout=30");
private void iconButton1_Click(object sender, EventArgs e)
{
newBalance = oldBalance + Convert.ToInt32(txtAmmount.Text);
try
{
connection.Open();
SqlDataAdapter adapter = new SqlDataAdapter();
adapter.MissingSchemaAction = MissingSchemaAction.AddWithKey;
adapter.SelectCommand = new SqlCommand("UPDATE Account SET AccBalance ='" + Convert.ToDouble(newBalance) + "'WHERE AccountNum =" + txtAccount.Text.Trim() + "", connection);
DataTable data = new DataTable();
adapter.Fill(data);
if (data.Rows.Count >0)
{
MessageBox.Show("Deposit Success", "Deposit", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
else
{
MessageBox.Show("Deposit Faild", "Deposit", MessageBoxButtons.OK, MessageBoxIcon.Warning);
}
connection.Close();
}
catch (Exception ex)
{
MessageBox.Show(" " + ex, "Warning", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
private void GetBalance()
{
try
{
connection.Open();
SqlDataAdapter adapter = new SqlDataAdapter();
adapter.MissingSchemaAction = MissingSchemaAction.AddWithKey;
AccountNumber =Form1.AccountNumber;
int accounts=Convert.ToInt32(AccountNumber);
adapter.SelectCommand = new SqlCommand("SELECT AccBalance FROM Account WHERE AccountNum='" + accounts + "'", connection);
DataTable data = new DataTable();
adapter.Fill(data);
oldBalance = Convert.ToInt32(data.Rows[0][0].ToString());
connection.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, "Warning Message!", MessageBoxButtons.OK, MessageBoxIcon.Warning);
}
}
private void Form3_Load(object sender, EventArgs e)
{
GetBalance();
}
When I load the Form, I get an error
Input string was not in a correct format

I think the error is here
UPDATE Account SET AccBalance ='" + Convert.ToDouble(newBalance) + "'WHERE AccountNum =" + txtAccount.Text.Trim() + ""
In the runtime, for example, newBalance = 1 and then txtAccount.Text = "My name" the result will be
UPDATE Account SET AccBalance ='1'WHERE AccountNum =My Name
As you can see:
No space between 1' and WHERE
No ' before and after "My Name"
That's why the code can't work and now you know how to fix it.
As some comment already above, you should use SQLCommand Params instead of building raw SQL string https://csharp-station.com/Tutorial/AdoDotNet/Lesson06

How to add textbox data to a database?

I am making a school project and i need to put text input (name and gender) into a database. This database (the names and genders) then have to be shown in a listbox. The code i have at the moment is put below, how can i make it work? Thanks in advance!
private void Form1_Load(object sender, EventArgs e)
{
using (connection = new SqlConnection(connectionString))
using (SqlDataAdapter adapter = new SqlDataAdapter("SELECT * FROM
Persoon", connection))
{
connection.Open();
DataTable PersoonTable = new DataTable();
adapter.Fill(PersoonTable);
lb_gebruikers.DisplayMember = "Naam";
lb_gebruikers.ValueMember = "Id";
lb_gebruikers.DataSource = PersoonTable;
}
}
private void button1_Click(object sender, EventArgs e)
{
string naam = tb_naam.Text;
string geslacht = tb_geslacht.Text;
Persoon nieuwpersoon = new Persoon(naam, geslacht);
personen.Add(nieuwpersoon);
foreach (var Persoon in personen)
{
lb_gebruikers.Items.Add("Naam: " + nieuwpersoon.Naam +
"Geslacht: " + nieuwpersoon.Geslacht);
}
}

As i understand you just have to add a insert between button1.click and addToList process.
private void btnSave_Click(object sender, EventArgs e)
{
try
{
SqlConnection con = new SqlConnection("Server =.;Database=People; Integrated Security = true");
con.Open();
SqlCommand cmd = new SqlCommand(); // you can define commandText and connection in SqlCommand(defineArea);
cmd.Connection = con; // like; cmd = newSqlCommand("Insert into...",con);
string name = txtName.Text;
string gender = txtGender.Text;
cmd.CommandText = "Insert into Person(Name,Gender)values('" + name + "','" + gender + "')";
cmd.ExecuteNonQuery();
cmd.Dispose();
con.Close();
lstBxPerson.Items.Add(name + " - " + gender);
MessageBox.Show("Save Success!");
}
catch (Exception ex)
{
MessageBox.Show("Exception : "+ex);
}
}
Database Name : People
Table Name : Person
All Parts Image :

Deleting mysql table entry with C#

Basically, what I want to delete an entry form a dataviewtable which pulls data through from MySql. I thought this would be done fairly by effectively copying the modify code and substituting it for 'DELETE'. However, from the code below, you can clearly see that hasn't worked. I will copy most of my code for you:
private void button1_Click(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection("Data Source=DESKTOP-HNR3NJB\\mysql;Initial Catalog=stock;Integrated Security=True");
var sqlQuery = "";
if (IfProductsExists(con, textboxProductID.Text))
{
con.Open();
sqlQuery = #"DELETE FROM [Products] WHERE [ProductID] = '" + textboxProductID.Text + "'";
SqlCommand cmd = new SqlCommand(sqlQuery, con);
cmd.ExecuteNonQuery();
con.Close();
}
else
{
MessageBox.Show("Record doesn't exist!", "ERROR:", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
//Reading Data
LoadData();
}
So that's the delete button's code now for the add button and load data function
Add button:
private void button2_Click(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection(#"Data Source=DESKTOP-HNR3NJB\mysql;Initial Catalog=stock;Integrated Security=True");
//insert logic
con.Open();
if(textboxProductID.Text == "" || textboxProductName.Text == "")
{
MessageBox.Show("You have to enter either a product ID or product name", "Error:", MessageBoxButtons.OK, MessageBoxIcon.Error);
return;
}
else
{
bool status = false;
if (comboboxStatus.SelectedIndex == 0)
{
status = true;
}
else
{
status = false;
}
var sqlQuery = "";
if (IfProductsExists(con, textboxProductID.Text))
{
sqlQuery = #"UPDATE [Products] SET [ProductName] = '" + textboxProductName.Text + "' ,[ProductStatus] = '" + status + "' WHERE [ProductID] = '" + textboxProductID.Text + "'";
}
else
{
sqlQuery = #"INSERT INTO [Stock].[dbo].[Products] ([ProductID],[ProductName],[ProductStatus]) VALUES
('" + textboxProductID.Text + "','" + textboxProductName.Text + "','" + status + "')";
}
SqlCommand cmd = new SqlCommand(sqlQuery, con);
cmd.ExecuteNonQuery();
con.Close();
textboxProductID.Clear();
textboxProductName.Clear();
LoadData();
}
}
LoadData function:
public void LoadData()
{
SqlConnection con = new SqlConnection(#"Data Source=DESKTOP-HNR3NJB\mysql;Initial Catalog=stock;Integrated Security=True");
//reading data from sql
SqlDataAdapter sda = new SqlDataAdapter("Select * From [stock].[dbo].[Products]", con);
DataTable dt = new DataTable();
sda.Fill(dt);
dataGridView1.Rows.Clear();
foreach (DataRow item in dt.Rows)
{
int n = dataGridView1.Rows.Add();
dataGridView1.Rows[n].Cells[0].Value = item["ProductID"].ToString();
dataGridView1.Rows[n].Cells[1].Value = item["ProductName"].ToString();
if ((bool)item["ProductStatus"])
{
dataGridView1.Rows[n].Cells[2].Value = "Active";
}
else
{
dataGridView1.Rows[n].Cells[2].Value = "Deactive";
}
}
}
You're going to need the IfProductsExists method too:
private bool IfProductsExists(SqlConnection con, string productCode)
{
SqlDataAdapter sda = new SqlDataAdapter("Select 1 From [Products] WHERE [ProductID]='" + productCode + "'", con);
DataTable dt = new DataTable();
if (dt.Rows.Count > 0)
return true;
else
return false;
}
It's going to be an inventory system that's going to be used at work for the sale and inventory management of IT equipment.

How to make dependent combo boxes work correctly

I have two combo boxes "Year" & "Amount" on the top of them I do get values for user info, because there are text boxes when called with user ID text boxes fill up with correct data.
The two combo boxes are also filled with correct data but I have to manually select year and the amount corresponding to it.
I need help in when I call the data "Year" & "Amount" should appear visible in the combo box. When I select a Year then the Amount should change accordingly. Last but not the least my reset is not clearing the combo boxes.
using System;
using System.Windows.Forms;
using System.Data.SqlClient;
using System.Data;
namespace dss
{
public partial class Form1 : Form
{
SqlConnection con = new SqlConnection("Data Source=USER-PC\\sqlexpress;Initial Catalog=JG_Test;Integrated Security=True");
public Form1()
{
InitializeComponent();
}
private void btnSearch_Click(object sender, EventArgs e)
{
cmbYear.Items.Clear();
string sql = "";
con.Open();
SqlCommand cmd = new SqlCommand();
try
{
sql += "SELECT m.MemberId, m.Name, m.Address, m.Cellular, m.Email, p.PaymentId, p.Year, p.Amount from Members as m";
sql += " INNER JOIN Payments as p ON m.MemberId = p.MemberId";
sql += " WHERE m.MemberId = '" + tbID.Text + "' ORDER BY p.Year ASC";
cmd.Connection = con;
cmd.CommandText = sql;
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataTable dt = new DataTable();
da.Fill(dt);
con.Close();
if(dt.Rows.Count >0)
{
for(int i = 0; i<=dt.Rows.Count -1;i++)
{
tbID.Text = dt.Rows[i]["MemberId"].ToString();
tbName.Text = dt.Rows[i]["Name"].ToString();
tbCellular.Text = dt.Rows[i]["Cellular"].ToString();
tbEmail.Text = dt.Rows[i]["Email"].ToString();
tbAddress.Text = dt.Rows[i]["Address"].ToString();
cmbAmount.Items.Add(dt.Rows[i]["Amount"].ToString());
cmbYear.Items.Add(dt.Rows[i]["Year"].ToString());
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message.ToString());
}
}
//This part displaying og the existing data from all the fileds corrssponding within the database//
private void btnAdd_Click(object sender, EventArgs e)
{
{
con.Open();
string Sql = "INSERT INTO Members ( MemberId, Name, Cellular, Email, Address ) VALUES " + " (#Id, #name, #cell, #email, #address)";
using (SqlCommand cmd = new SqlCommand(Sql, con))
{
cmd.CommandText = Sql;
cmd.Parameters.AddWithValue("#Id", tbID.Text);
cmd.Parameters.AddWithValue("#name", tbName.Text);
cmd.Parameters.AddWithValue("#cell", tbCellular.Text);
cmd.Parameters.AddWithValue("#email", tbCellular.Text);
cmd.Parameters.AddWithValue("#address", tbAddress.Text);
cmd.ExecuteNonQuery();
Sql = "INSERT INTO Payments ( MemberId, [Year], [Amount] ) VALUES " + " (#Id, Amount, Year)";
cmd.Parameters.Clear();
cmd.CommandText = Sql;
cmd.Parameters.AddWithValue("#Id", tbID.Text);
cmd.Parameters.AddWithValue("#year", cmbYear.Text);
cmd.Parameters.AddWithValue("#amount", cmbAmount.Text);
cmd.ExecuteNonQuery();
MessageBox.Show("Data Added");
tbID.Clear(); tbName.Clear(); tbCellular.Clear(); tbEmail.Clear(); tbAddress.Clear(); cmbYear.Items.Clear(); cmbAmount.Items.Clear();
con.Close();
}
}
}
//This part represents adding of new input data from all the fileds into the database//
private void btnUpdate_Click(object sender, EventArgs e)
{
try
{
SqlCommand cmd = new SqlCommand();
string Sql = "UPDATE Members SET MemberId = '" + tbID.Text + "', Name = '" + tbName.Text + "', Cellular = '" + tbCellular.Text + "', Email = '" + tbEmail.Text + "', Address = '" + tbAddress.Text + "' WHERE MemberId = '" + tbID.Text + "' ";
cmd.CommandText = Sql;
cmd.Connection = con;
con.Open();
cmd.ExecuteNonQuery();
con.Close();
Sql = "UPDATE Payments SET MemberId = '" + tbID.Text + "', Year = '" + cmbYear.Text + "', Amount = '" + cmbAmount.Text + "' WHERE MemberId = '" + tbID.Text + "' ";
cmd.CommandText = Sql;
cmd.Connection = con;
con.Open();
cmd.ExecuteNonQuery();
con.Close();
MessageBox.Show("Data Updated");
tbID.Clear(); tbName.Clear(); tbAddress.Clear(); tbCellular.Clear(); tbEmail.Clear(); cmbYear.Items.Clear(); cmbAmount.Items.Clear();
}
catch (Exception error)
{
MessageBox.Show(error.ToString());
}
}
//This part represents deleteing of input data from all the fileds into the database//
private void btnDelete_Click(object sender, EventArgs e)
{
try
{
SqlCommand cmd = new SqlCommand();
string Sql = "DELETE FROM Members WHERE MemberId = '" + tbID.Text + "' ";
cmd.CommandText = Sql;
cmd.Connection = con;
con.Open();
cmd.ExecuteNonQuery();
con.Close();
Sql = "DELETE FROM Payments WHERE MemberId = '" + tbID.Text + "' ";
cmd.CommandText = Sql;
cmd.Connection = con;
con.Open();
cmd.ExecuteNonQuery();
tbID.Clear(); tbName.Clear(); tbAddress.Clear(); tbCellular.Clear(); tbEmail.Clear(); cmbYear.Items.Clear(); cmbAmount.Items.Clear();
MessageBox.Show("Data Deleted");
con.Close();
}
catch (Exception error)
{
MessageBox.Show(error.ToString());
}
}
//This part represents clearing of input data from all the fileds//
private void btnReset_Click(object sender, EventArgs e)
{
tbID.Clear(); tbName.Clear(); tbAddress.Clear(); tbCellular.Clear(); tbEmail.Clear(); cmbYear.Items.Clear(); cmbAmount.Items.Clear();
}
//This part represents shuting down the application//
private void btnExit_Click(object sender, EventArgs e)
{
Application.Exit();
}
}
}

I would be inclined to simplify things a bit. Treat the personal data and the finance data as 2 parts.
Firstly, request the personal data - keep it simple
private void btnSearch_Click(object sender, EventArgs e)
{
string sql = "SELECT MemberId, Name, Address, Cellular, Email FROM Members WHERE MemberId = #Id";
SqlConnection con = new SqlConnection("myconnectionstring");
SqlCommand cmd = new SqlCommand(sql,con);
cmd.Parameters.Add("#Id",SqlDbType.Int).Value = tbID.Text;
DataTable dt = new DataTable();
try
{
con.Open();
dt.Load(cmd.ExecuteReader());
con.Close();
}
catch (Exception ex)
{
con.Close();
Console.WriteLine(ex.Message);
}
tbID.Text = dt.Rows[0]["MemberId"].ToString();
tbName.Text = dt.Rows[0]["Name"].ToString();
tbCellular.Text = dt.Rows[0]["Cellular"].ToString();
tbEmail.Text = dt.Rows[0]["Email"].ToString();
tbAddress.Text = dt.Rows[0]["Address"].ToString();
}
Once thats done, move on to second part - the years/amounts combo (which is almost identical code)
string sql = "SELECT Year, Amount FROM Payments WHERE MemberId = #Id"
SqlConnection con = new SqlConnection("myconnectionstring");
SqlCommand cmd = new SqlCommand(sql,con);
cmd.Parameters.Add("#Id",SqlDbType.Int).Value = tbID.Text;
DataTable dt = new DataTable();
try
{
con.Open();
dt.Load(cmd.ExecuteReader());
con.Close();
}
catch (Exception ex)
{
con.Close();
Console.WriteLine(ex.Message);
}
cmbYear.DataSource = dt;
cmbYear.DisplayMember = "Year";
cmbYear.ValueMember = "Amount";
And finally, tell the textbox what it needs to read by using
private void cmbYear_SelectionChangeCommitted(object sender, EventArgs e)
{
amountTxt.Text = cmbYear.SelectedValue.ToString();
}
in the combobox's SelectionChangeCommitted event
And that should have you sorted!

Retrieve Database values and show them on form using SQLDataReader

I am trying to retrieve data from a Database and show them on a form; but my code isn't working... I've got no errors, and logically it seems to work (to me) so I cannot figure out where I have gone wrong. That's where I need your help!
private void tableListBox_SelectedIndexChanged(object sender, EventArgs e)
{
string constring = #"Data Source=(LocalDB)\v11.0;AttachDbFilename=|DataDirectory|\IncomerDefault.mdf;Integrated Security=True;Connect Timeout=30";
string Query = "SELECT * FROM [Table] WHERE Default_Name = '" + tableListBox.SelectedValue + "'";
SqlConnection con = new SqlConnection(constring);
SqlCommand cmd = new SqlCommand(Query, con);
SqlDataReader Reader;
try
{
con.Open();
Reader = cmd.ExecuteReader();
while (Reader.Read())
{
textBox1.Text = Reader.GetValue(2).ToString();
comboBox1.Text = Reader.GetValue(3).ToString();
comboBox3.Text = Reader.GetValue(4).ToString();
textBox2.Text = Reader.GetValue(6).ToString();
comboBox2.Text = Reader.GetValue(7).ToString();
comboBox4.Text = Reader.GetValue(8).ToString();
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
con.Close();
}
The 'tableListBox' is populated with all the values in column 'Default_Name'. I want it so that when the 'Default_Name' is selected from the list box it shows the values, in textboxes and comboboxes, that correspond with that row in the Database.
Any and all help would be appreciated. Thanks.

I'm going to start by changing your design a bit and suggest that perhaps you look at using a datatable and then just retrieving the rows from the datatable.
private void tableListBox_SelectedIndexChanged(object sender, EventArgs e)
{
private DataTable dataTable;
string constring = #"Data Source=(LocalDB)\v11.0;AttachDbFilename=|DataDirectory|\IncomerDefault.mdf;Integrated Security=True;Connect Timeout=30";
string Query = "SELECT * FROM [Table] WHERE Default_Name = '" + tableListBox.SelectedValue + "'";
SqlConnection con = new SqlConnection(constring);
SqlCommand cmd = new SqlCommand(Query, con);
try
{
con.Open();
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(dataTable);
foreach(DataRow row in dataTable.Rows)
{
textBox1.Text = row[2].ToString();
comboBox1.Text = row[3].ToString();
comboBox3.Text = row[4].ToString();
textBox2.Text = row[6].ToString();
comboBox2.Text = row[7].ToString();
comboBox4.Text = row[8].ToString();
}
da.Dispose();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
con.Close();
}
I generally find that DataTables are more reliable than looping through the actual reader. Ofcourse this assumes that there is data being returned. Also try changing your select statement to this
string Query = "SELECT * FROM [Table]"
If that works, then the problem could be
There is no default name of the specified value or
tableListBox.SelectedValue is not returning any value, in which case, have a look at your listbox selected value

Thanks to Takarii for helping. I figured out who to make it work.
private void tableListBox_SelectedValueChanged(object sender, EventArgs e)
{
string constring = #"Data Source=(LocalDB)\v11.0;AttachDbFilename=|DataDirectory|\IncomerDefault.mdf;Integrated Security=True;Connect Timeout=30";
string Query = "SELECT * FROM [Table] WHERE ID = '" + tableListBox.SelectedIndex.ToString() + "'";
SqlConnection con = new SqlConnection(constring);
SqlCommand cmd = new SqlCommand(Query, con);
SqlDataReader Reader;
try
{
con.Open();
Reader = cmd.ExecuteReader();
while (Reader.Read())
{
textBox1.Text = Reader.GetValue(2).ToString();
comboBox1.Text = Reader.GetValue(3).ToString();
comboBox3.Text = Reader.GetValue(4).ToString();
textBox2.Text = Reader.GetValue(6).ToString();
comboBox2.Text = Reader.GetValue(7).ToString();
comboBox4.Text = Reader.GetValue(8).ToString();
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
con.Close();
}
First I changed the void to 'SelectedValueChanged' and then I changed the 'WHERE' in the connection Query to the Row Index associated with the selected Value.
Thanks for everyone's help!