Linking combobox to combobox

Драгана Тошовић

Hello guys,

can someone please tell me how to create a connection between two comboBoxes? For example, I have CPU brands in comboBox1, and I need to create a link to filter choices in comboBox2 ( where I have models of CPU) when I pick some brand from combobox1. My program is connected to database in MSSMS where I have all the data I need for my program.

Any help would be good, thank you in advance :)

2 Replies

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Драгана Тошовић6y ago
I acctually tried this solution down bellow. The problem is, the commented part of the code works, but it isn't placing the right models or order, and the non commented part doesn't work, my comboBox3 is blank. :/
try
{
SqlCommand sc = new SqlCommand();
con.Open();
if (comboBox1.SelectedItem.ToString() == "Asus")
sc = new SqlCommand("select distinct (model) from MaticnaPloca where Proizvodjac = 'Asus' AND Soket = '1151'", con);
if (comboBox1.SelectedItem.ToString() == "Asus")
sc = new SqlCommand("select distinct(model) from MaticnaPloca where Proizvodjac = 'Asus' AND Soket = 'AM4' ", con);
if (comboBox1.SelectedItem.ToString() == "Asus")
sc = new SqlCommand("select distinct(model) from MaticnaPloca where Proizvodjac = 'Asus' AND Soket = 'TR4' ", con);
//if (comboBox1.SelectedIndex == 3)
// sc = new SqlCommand("select distinct(model) from MaticnaPloca where Proizvodjac = 'Biostar' AND Soket = 'AM4' ", con);
//if (comboBox1.SelectedIndex == 4)
// sc = new SqlCommand("select distinct(model) from MaticnaPloca where Proizvodjac = 'Biostar' AND Soket = '1151' ", con);
//if (comboBox1.SelectedIndex == 5)
// sc = new SqlCommand("select distinct(model) from MaticnaPloca where Proizvodjac = 'Gigabyte' AND Soket = '1151' ", con);
//if (comboBox1.SelectedIndex == 6)
// sc = new SqlCommand("select distinct(model) from MaticnaPloca where Proizvodjac = 'Gigabyte' AND Soket = 'AM4' ", con);
//if (comboBox1.SelectedIndex == 7)
// sc = new SqlCommand("select distinct(model) from MaticnaPloca where Proizvodjac = 'Gigabyte' AND Soket = 'TR4' ", con);
//if (comboBox1.SelectedIndex == 8)
// sc = new SqlCommand("select distinct(model) from MaticnaPloca where Proizvodjac = 'MSI' AND Soket = 'AM4' ", con);
//if (comboBox1.SelectedIndex == 9)
// sc = new SqlCommand("select distinct(model) from MaticnaPloca where Proizvodjac = 'MSI' AND Soket = 'TR4' ", con);
SqlDataReader reader;
reader = sc.ExecuteReader();
DataTable dt2 = new DataTable();
dt2.Columns.Add("model", typeof(string));
dt2.Load(reader);
comboBox3.ValueMember = "model";
comboBox3.DataSource = dt2;
comboBox3.SelectedIndex = -1;
comboBox3.Enabled = true;
con.Close();
}
catch (Exception)
{
}
Suraj Kumar6y ago
You can simply pass the selected item either values or text of fist combo box in where condition while loading the second combo box.

For this you need to relate the second table to fist one using primary & foreign key.
public void refreshstate(int countryid)
{

            con.Open();
            SqlCommand cmd = new SqlCommand("select * from tbl_state where countryid= @countryid", con);
            cmd.Parameters.AddWithValue("countryid", countryid);
            SqlDataAdapter sda = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            sda.Fill(dt);
            con.Close();
            dr = dt.NewRow();
            dr.ItemArray = new object[] { 0, "--Select State--" };
            dt.Rows.InsertAt(dr, 0);

            comboBox2.ValueMember = "stateid";
            comboBox2.DisplayMember = "statename";
            comboBox2.DataSource = dt;
}
For more information you can follow the source link given below - example of Cascading combox.

https://www.c-sharpcorner.com/UploadFile/009464/cascading-combobox-in-windows-application-using-C-Sharp/