CODEWITHSUNDEEP
c#winforms
Matt Wilkinson
Matt Wilkinson

Reputation: 99

Updating data from combobox C#

What i am trying to do is when a user selects a company from a comboBox then clicks the button the different text boxes are supposed to show the different data from the database.

This is what i have but it doesnt seem to work.

Any suggestions?

private void Edit_Load(object sender, EventArgs e)
    {

        using (SqlConnection con = new SqlConnection(str))
        {
            con.Open();
            SqlDataAdapter adapt = new SqlDataAdapter("SELECT * FROM Companies", con);
            DataTable dt = new DataTable();
            adapt.Fill(dt);
            comboBox1.DataSource = dt;
            comboBox1.DisplayMember = "Name";




        }
    }

private void button3_Click(object sender, EventArgs e)
    {
        String company = comboBox1.SelectedItem.ToString();
        String check = @"SELECT * FROM Companies WHERE Name=@name";
        using (SqlConnection con = new SqlConnection(str))
        using (SqlCommand cmd = new SqlCommand(check, con))
        {
            con.Open();
            cmd.Parameters.Add("@name", SqlDbType.VarChar).Value = company;



            SqlDataReader reader = cmd.ExecuteReader();

            while (reader.Read())
            {
                textBox1.Text = (reader["Name"].ToString());
                textBox2.Text = (reader["PhNo"].ToString());
                textBox3.Text = (reader["Email"].ToString());
                textBox4.Text = (reader["Acc"].ToString());
                textBox5.Text = (reader["Address"].ToString());
                textBox6.Text = (reader["Suburb"].ToString());
                textBox7.Text = (reader["PostCode"].ToString());
                textBox8.Text = (reader["State"].ToString());

            }


        }
    }

Update: the output of comboBox1.SelectedItem.ToString(); is System.Data.DataRowView so it seems to not be registering what the selected item is. How do i resolve this?

Upvotes: 1

Views: 1510

Answers (3)

Reza Aghaei
Reza Aghaei

Reputation: 125312

When the DataSource of your combo box is a DataTable, then the object in SelectedItem is of type DataRowView.

So to get a field, you can cast selected item to DataRowView and extract the field value this way:

var name = ((DataRowView)comboBox1.SelectedItem)["Name"].ToString();

In fact ((DataRowView)comboBox1.SelectedItem)["FieldName"] is of type object and you should cast the field to the desired type.

Upvotes: 2

Mobeen Rashid
Mobeen Rashid

Reputation: 13

Try the code below it will work,the thing that you are missing is you are not setting the ValueMember property of your combo box.

Suggestion : 1.Debug your code and make sure that your query is correct and your able to getting the value right values from data source. 2.Make sure that your columns names in your database table are exactly same as you are setting in your combo box display member and value member

 using (SqlConnection connection = new SqlConnection("Data Source=.;Initial Catalog=\"Student Extended\";Integrated Security=True"))
                {
                    SqlCommand command = new SqlCommand
                    {
                        Connection = connection,
                        CommandText = "SELECT DepartmentId,DepartmentName FROM dbo.TblDepartment"
                    };
                    SqlDataAdapter adpater = new SqlDataAdapter(command);
                    DataTable table = new DataTable();
                    adpater.Fill(table);
                    if (txtStdDeptName != null)
                    {
                        txtStdDeptName.DataSource = table;
                        txtStdDeptName.DisplayMember = "DepartmentName";
                        txtStdDeptName.ValueMember = "DepartmentId";
                    }
                }

Upvotes: 0

Freelancer
Freelancer

Reputation: 73

Try this

String check = "SELECT * FROM Companies WHERE Name=@name";
using (SqlConnection con = new SqlConnection("Data Source=(local);Initial Catalog=ABCD;Integrated Security=True"))
using (SqlCommand cmd = new SqlCommand(check, con))
{
  con.Open();
  cmd.Parameters.Add("@name", SqlDbType.VarChar).Value = comboBox1.SelectedItem.ToString();
  SqlDataReader reader = cmd.ExecuteReader();

  while (reader.Read())
  {
       textBox1.Text = reader["Name"].ToString();
       textBox2.Text = reader["PhNo"].ToString();
       textBox3.Text = reader["Email"].ToString();
       textBox4.Text = reader["Acc"].ToString();
       textBox5.Text = reader["Address"].ToString();
       textBox6.Text = reader["Suburb"].ToString();
       textBox7.Text = reader["PostCode"].ToString();
       textBox8.Text = reader["State"].ToString();

   }
}

Make sure your connectionstring is proper. Also Have you checked value of comboBox1.SelectedItem.ToString() and same is present in db?

If you are populating drop down from database then refer this: System.Data.DataRowView in DropDownList

Updated:

private void ComboBoxBinding()
{

    using (SqlConnection con = new SqlConnection(str))
    {
        con.Open();
        SqlDataAdapter adapt = new SqlDataAdapter("SELECT Name,Id FROM Companies", con);
        DataTable dt = new DataTable();
        adapt.Fill(dt);
        comboBox1.DisplayMember = "Name";
        comboBox1.ValueMember = "Id";
        comboBox1.DataSource = dt;

comboBox1.DataBind();


    }
}

You can call this function either in page load or in class constructor.

Upvotes: 0

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