Develop Reference

Data type mismatch in criteria expression(Convert.ToInt32(cmd.ExecuteScalar());)

I am trying to Display a name in the textbox from the database if the ID entered by the user matches the record in the MS ACCESS DATABASE.
I'm getting the error Data type mismatch in criteria expression at the line int count = Convert.ToInt32(cmd.ExecuteScalar());
The following is my aspx.cs code-
protected void Button1_Click(object sender, EventArgs e)
{
clear();
idcheck();
DataTable dt = new DataTable();
OleDbConnection con = new OleDbConnection(#"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Users\dfg\fd\Visual Studio 2010\WebSites\WebSite21\App_Data\UPHealth.mdb");
con.Open();
str = "SELECT [DoctorName] FROM [DoctorInfo] WHERE DoctorID='" + TextBox1.Text.Trim() + "'";
OleDbCommand cmd = new OleDbCommand(str, con);
OleDbDataReader dr = cmd.ExecuteReader();
if (dr.Read())
{
TextBox2.Text = dr["DoctorID"].ToString();
dr.Close();
con.Close();
}
}
public void idcheck()
{
OleDbConnection con = new OleDbConnection(#"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Users\dfg\fd\Visual Studio 2010\WebSites\WebSite21\App_Data\UPHealth.mdb");
con.Open();
str = "SELECT count(DoctorName) FROM [DoctorInfo] WHERE DoctorID='" + TextBox1.Text.Trim() + "'";
OleDbCommand cmd = new OleDbCommand(str, con);
int count = Convert.ToInt32(cmd.ExecuteScalar());
if (count > 0)
{
Label21.Text = "Doctor Name";
}
else
{
Label21.Text = "Id Does not Exist";
}
}
void clear()
{
TextBox2.Text = "";
}

I guess that is because you as passing in an ID, which is usually a numeric value, as a text field:
DoctorID='" + TextBox1.Text.Trim() + "'
Which should be:
DoctorID=" + TextBox1.Text.Trim()
Another problem arises, since you are vulnerable to SQL injection. What if the text box contained 1; delete users? Then your entire users table would be empty. The lesson learned: use parameterized queries!
Then you can express the SQL as:
DoctorID= ?
And add the parameter to the request:
cmd.Parameters.AddWithValue("?", TextBox1.Text.Trim());

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!

The error says "The ConnectionString property has not been initialized" in c#

this code is for the combo box where i want to select some index to show it to my textboxes.
private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
{
try
{
conn.Open();
cmd.Connection = conn;
string query = "SELECT * FROM GuestInfo WHERE Groomno= '" + comboBox2.Text + "'";
db.connectDB();
db.da.SelectCommand = new OleDbCommand(query, db.conn);
db.executeQryCommand(query, false);
maxRecord = db.ds.Tables[0].Rows.Count;
loadRecords(recordCounter);
cmd.CommandText = query;
dr = cmd.ExecuteReader();
while (dr.Read())
{
textBox1.Text = dr["Gname"].ToString();
textBox2.Text = dr["Gcontactno"].ToString();
}
conn.Close();
}
catch (Exception er)
{
MessageBox.Show("Error! " + er.Message);
}
}
//My program is completely running but not in this section. :(

Is you made an connection between your application and database source using conn object ? You might be used conn object as a connection object but before this was you initialized you Connection ?
Simpy use like
"SqlConnection conn=new SqlConnection("Connection_Source");"
here is your error.

You have to define the connection string for the connection, here i suggest you one best method for executing command.
using (OleDbConnection conn = new OleDbConnection("yourconnectionString"))
{
conn.Open();
using (OleDbCommand cmd =new OleDbCommand("your query text", conn))
{
// execute your command
}
}

If its just to select value from comboBox and display in textBox , then below code will help you...
private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
{
try
{
conn.Open();
OleDbCommand cmd = new OleDbCommand("SELECT Gname,Gcontactno FROM GuestInfo WHERE Groomno= '" + comboBox2.Text + "'", conn);
OleDbDataReader dr = cmd.ExecuteReader();
while (dr.Read())
{
textBox1.Text = dr[0].ToString();
textBox2.Text = dr[1].ToString();
}
conn.Close();
}
catch (Exception er)
{
MessageBox.Show("Error! " + er.Message);
}
}

MS Access database not updating

Can anybody tell me why my database isn't updating? Here's my code:
protected void editSection_selected(object sender, EventArgs e) {
int index = grdPhone.SelectedIndex;
GridViewRow row = grdPhone.Rows[index+1];
string values = ((DropDownList)sender).SelectedValue;
int tempVal = Convert.ToInt32(values);
int caseage = Convert.ToInt32(keyId);
int value = tempVal;
/*OleDbConnection con = new OleDbConnection(strConnstring);
//string query = "Update Categories set HRS_LEVEL_AMOUNT=" + tempVal + " where parent_id=65 and ID=" + caseage;
string query = "Delete HRS_LEVEL_AMOUNT from Categories where parent_id=65 and id=" + caseage;
OleDbCommand cmd = new OleDbCommand(query, con);
con.Open();
cmd.ExecuteNonQuery();
con.Dispose();
cmd.Dispose();
con.Close();
accPhoneNumbers.UpdateCommand = "Update Categories set HRS_LEVEL_AMOUNT=" + tempVal + " where parent_id=65 and ID=" + caseage;
*/
string str = "UPDATE Categories SET HRS_LEVEL_AMOUNT = ? WHERE ID=?";
using (OleDbConnection con = new OleDbConnection(strConnstring))
{
using (OleDbCommand cmd = new OleDbCommand(str, con))
{
cmd.CommandType = CommandType.Text;
cmd.Parameters.AddWithValue("HRS_LEVEL_AMOUNT", tempVal);
cmd.Parameters.AddWithValue("ID", caseage);
con.Open();
cmd.ExecuteNonQuery();
}
}
Label1.Text += " editSection Success! (B) " + tempVal;
}
The commented part is my first solution (including the accPhoneNumbers.UpdateCommand).
I really need your help guys.

I hope this can help you:
string str = "UPDATE Categories SET HRS_LEVEL_AMOUNT = #value1 WHERE ID=#value2";
using (OleDbConnection con = new OleDbConnection(strConnstring))
{
using (OleDbCommand cmd = new OleDbCommand(str, con))
{
cmd.CommandType = CommandType.Text;
cmd.Parameters.AddWithValue("#value1", tempVal);
cmd.Parameters.AddWithValue("#value2", caseage);
con.Open();
cmd.ExecuteNonQuery();
con.close();
}
}
For more information you can visit this video