how to fetch statename based on country

R.D Ip

5y873.NET

I am working on windows form application c sharp

I am trying to fetch statename based on country in combobox

now I am stuck and my logic is not work,which place need to correction

first I fetch a country name in combobox successfully

now I am trying to fetch statename based on country but my logic is not work

sp : load country

sp : load state based on country

code:

private void Form1_Load_1(object sender, EventArgs e) //load country successfully in combobox
{
cnnString.Open();
SqlCommand cmd = new SqlCommand("sp_LoadCountry", cnnString);
SqlDataReader reader = cmd.ExecuteReader();
DataTable dt = new DataTable();
dt.Columns.Add("countryid");
dt.Columns.Add("countryname");
dt.Load(reader);
countrycomboBox.ValueMember = "countryid";
countrycomboBox.DisplayMember = "countryname";
countrycomboBox.DataSource = dt;
cnnString.Close();
}
private void countrycomboBox_SelectedIndexChanged(object sender, EventArgs e) //here I am stuck state not load based on country
{
SqlCommand cmd = new SqlCommand("sp_LoadStateBaseOnCountry", cnnString);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("countryid",countrycomboBox.Items.IndexOf(cmd));
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(dt);
statecomboBox.ValueMember = "stateid";
statecomboBox.DisplayMember = "statename";
statecomboBox.DataSource = dt;
}

output:

now I am stuck in logic need help

11 Replies

Know the answer? Post it — somebody with the same question will find it here.

Sachin Singh5y ago
when items are cleared then there is no chance of duplicate , i can't guess what is happening in your case.
+1
R.D Ip5y ago
error is not come but issue is not solved
private void countrycomboBox_SelectedIndexChanged(object sender, EventArgs e)
        {
            statecomboBox.DataSource = null;
            statecomboBox.Items.Clear();
            ComboBox cmb = (ComboBox)sender;

            string selectedValue = (string)cmb.SelectedValue;
            BindStateByCountry(selectedValue);
        }
private void Form1_Load_1(object sender, EventArgs e)
        {

            countrycomboBox.DataSource = null;
            countrycomboBox.Items.Clear();
            statecomboBox.DataSource = null;
            statecomboBox.Items.Clear();
            BindCountry();
        }
+1
Sachin Singh5y ago
hey
please test with making datasource null as well
private void countrycomboBox_SelectedIndexChanged(object sender, EventArgs e)    //here I am stuck state not load based on country
{
     countrycomboBox.DataSource=null;
      countrycomboBox.Items.Clear();
     statecomboBox.DataSource=null;
     statecomboBox.Items.Clear();
     ComboBox cmb = (ComboBox)sender;

    int selectedValue = (int)cmb.SelectedValue;
     BindStateByCountry(selectedValue);

}
private void Form1_Load_1(object sender, EventArgs e)   //load country successfully in combobox
{
countrycomboBox.DataSource=null;
    countrycomboBox.Items.Clear();
     BindCountry();
     statecomboBox.DataSource=null;
          statecomboBox.Items.Clear();
}
+1
R.D Ip5y ago
1. private void countrycomboBox_SelectedIndexChanged(object sender, EventArgs e)
2. {
3. statecomboBox.Items.Clear(); //here give an error second time when I select usa then give an eror
4. ComboBox cmb = (ComboBox)sender;
6. string selectedValue = (string)cmb.SelectedValue;
7. BindStateByCountry(selectedValue);
8. }
9. private void Form1_Load_1(object sender, EventArgs e)
  {
  countrycomboBox.Items.Clear();
  BindCountry();
  }
+1

Sachin Singh5y ago

okk then clear it on form load

private void Form1_Load_1(object sender, EventArgs e) //load country successfully in combobox
{
countrycomboBox.Items.Clear();
BindCountry();
statecomboBox.Items.Clear();
}
private void BindCountry()
{
cnnString.Open();
SqlCommand cmd = new SqlCommand("sp_LoadCountry", cnnString);
SqlDataReader reader = cmd.ExecuteReader();
DataTable dt = new DataTable();
dt.Columns.Add("countryid");
dt.Columns.Add("countryname");
dt.Load(reader);
countrycomboBox.ValueMember = "countryid";
countrycomboBox.DisplayMember = "countryname";
countrycomboBox.DataSource = dt;
cnnString.Close();
}
private void BindStateByCountry(int CountryId)
{
SqlCommand cmd = new SqlCommand("sp_LoadStateBaseOnCountry", cnnString);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("countryid",CountryId); // here
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(dt);
statecomboBox.ValueMember = "stateid";
statecomboBox.DisplayMember = "statename";
statecomboBox.DataSource = dt;
}
private void countrycomboBox_SelectedIndexChanged(object sender, EventArgs e) //here I am stuck state not load based on country
{
statecomboBox.Items.Clear();
ComboBox cmb = (ComboBox)sender;
int selectedValue = (int)cmb.SelectedValue;
BindStateByCountry(selectedValue);
}

R.D Ip5y ago

hello sachin

below line give an error:

Items collection cannot be modified when the DataSource property is set.

countrycomboBox.Items.Clear(); //Items collection cannot be modified when the DataSource property is set.

Sachin Singh5y ago

modify them as shown below, also keep code cleaner as i am doing.

private void Form1_Load_1(object sender, EventArgs e) //load country successfully in combobox
{
BindCountry();
}
private void BindCountry()
{
cnnString.Open();
SqlCommand cmd = new SqlCommand("sp_LoadCountry", cnnString);
SqlDataReader reader = cmd.ExecuteReader();
DataTable dt = new DataTable();
dt.Columns.Add("countryid");
dt.Columns.Add("countryname");
dt.Load(reader);
countrycomboBox.ValueMember = "countryid";
countrycomboBox.DisplayMember = "countryname";
countrycomboBox.DataSource = dt;
cnnString.Close();
}
private void BindStateByCountry(int CountryId)
{
SqlCommand cmd = new SqlCommand("sp_LoadStateBaseOnCountry", cnnString);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("countryid",CountryId); // here
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(dt);
statecomboBox.ValueMember = "stateid";
statecomboBox.DisplayMember = "statename";
statecomboBox.DataSource = dt;
}
private void countrycomboBox_SelectedIndexChanged(object sender, EventArgs e) //here I am stuck state not load based on country
{
countrycomboBox.Items.Clear();
statecomboBox.Items.Clear();
ComboBox cmb = (ComboBox)sender;
int selectedValue = (int)cmb.SelectedValue;
BindStateByCountry(selectedValue);
}

R.D Ip5y ago

hello sachin your answer is work but problem is when I select another country then previous state and current country state is together now can you help more

see my output:

private void countrycomboBox_SelectedIndexChanged(object sender, EventArgs e)
{
ComboBox cmb = (ComboBox)sender;
string selectedValue = (string)cmb.SelectedValue;
SqlCommand cmd = new SqlCommand("sp_LoadStateBaseOnCountry", cnnString);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("countryid", selectedValue);
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(dt);
statecomboBox.ValueMember = "stateid";
statecomboBox.DisplayMember = "statename";
statecomboBox.DataSource = dt;
}

both country's state are together now what is solution ?

Sachin Singh5y ago

a little modification

private void Form1_Load_1(object sender, EventArgs e) //load country successfully in combobox
{
cnnString.Open();
SqlCommand cmd = new SqlCommand("sp_LoadCountry", cnnString);
SqlDataReader reader = cmd.ExecuteReader();
DataTable dt = new DataTable();
dt.Columns.Add("countryid");
dt.Columns.Add("countryname");
dt.Load(reader);
countrycomboBox.ValueMember = "countryid";
countrycomboBox.DisplayMember = "countryname";
countrycomboBox.DataSource = dt;
cnnString.Close();
}
private void countrycomboBox_SelectedIndexChanged(object sender, EventArgs e) //here I am stuck state not load based on country
{
ComboBox cmb = (ComboBox)sender;
int selectedValue = (int)cmb.SelectedValue;
SqlCommand cmd = new SqlCommand("sp_LoadStateBaseOnCountry", cnnString);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("countryid",selectedValue ); // here
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(dt);
statecomboBox.ValueMember = "stateid";
statecomboBox.DisplayMember = "statename";
statecomboBox.DataSource = dt;
}

Salman Beg5y ago

Check this, https://docs.microsoft.com/en-us/dotnet/api/system.windows.forms.combobox.selectedindexchanged?view=net-5.0 https://www.c-sharpcorner.com/forums/get-textbox-value-based-on-combobox-selectedindexchanged https://www.aspsnippets.com/Articles/Get-Selected-Text-and-Value-of-ComboBox-in-Windows-Application-using-C-and-VBNet.aspx

Salman Beg5y ago

Hey. Probably first check what value you are getting for countrycomboBox in countrycomboBox_SelectedIndexChanged method. Also you can refer these links as an example and recty code if any, https://www.webcodeexpert.com/2013/07/how-to-fill-countrystatecities-in.html?m=1 https://www.c-sharpcorner.com/UploadFile/rohatash/dropdownlist-with-country-state-and-city-in-asp-net/