populate 2nd combobox based on the 1st combobox

DataSet ds; String strConn="Server=CHEETAH;Database=NorthWind;Trusted_Connection=True;"; private void Form1_Load(object sender, EventArgs e) { using (SqlConnection conn = new SqlConnection(strConn )) { ds = new DataSet(); SqlDataAdapter daCat = new SqlDataAdapter("SELECT [CategoryID],[CategoryName] FROM Categories", conn ); daCat.Fill(ds, "Categories"); comboBox1.DisplayMember = "CategoryName"; comboBox1.ValueMember = "CategoryID"; comboBox1.DataSource = ds.Tables["Categories"]; } } private void comboBox1_SelectedIndexChanged(object sender, EventArgs e) { using (SqlConnection conn = new SqlConnection(strConn )) { SqlDataAdapter daProd = new SqlDataAdapter("SELECT [ProductID], [ProductName] FROM Products WHERE CategoryID = @CategoryID", conn); daProd.SelectCommand.Parameters.AddWithValue("@CategoryID", comboBox1.SelectedValue); daProd.Fill(ds, "Products"); comboBox2.DisplayMember = "ProductName"; comboBox2.ValueMember = "ProductID"; comboBox2.DataSource = ds.Tables["Products"]; } } private void comboBox2_SelectedIndexChanged(object sender, EventArgs e) { using (SqlConnection conn = new SqlConnection(Properties.Settings.Default.dbConnectionString)) { SqlDataAdapter daProdDesc = new SqlDataAdapter("SELECT [ProductID], [Description] FROM Products WHERE CategoryID=@CategoryID", conn); daProdDesc.SelectCommand.Parameters.AddWithValue("@CategoryID", comboBox2.SelectedValue); daProdDesc.Fill(ds, "Products"); listBox1.DataSource = ds.Tables["Products"]; listBox1.DisplayMember = "Description"; listBox1.ValueMember = "ProductID"; } } this is my code for this.. its working but not perfectly. on the form load, category name displays as well as its corresponding products. but when i change to 2nd category for example, its corresponding products list is added to the previous list. meaning products for category 1&2 are displayed.. i have also added another code for displaying the product's description in a listbox. but the problem is that all the descriptions of all the products are being displayed. i just want to display description of the selected product.

daProd.SelectCommand.Parameters.Add("@CategoryID", SqlDbType.Int).Value=comboBox1.SelectedIndex; change the above to: daProd.SelectCommand.Parameters.Add("@CategoryID", SqlDbType.Int).Value=comboBox1.SelectedValue;

ok! i have corrected my code for the 1st combobox. but as what i've said adding the code below has no effect on the my 2nd combobox. nothing shows when i choose item from the 1st combobox what maybe the problem? comboBox1_SelectedIndexChanged(object sender, EventArgs e) { using (SqlConnection conn = new SqlConnection(Properties.Settings.Default.dbConnectionString)) { SqlDataAdapter daProd = new SqlDataAdapter("SELECT [ProductID], [ProductName] FROM Products WHERE CategoryID = @CategoryID", conn); daProd.SelectCommand.Parameters.Add("@CategoryID", SqlDbType.Int).Value=comboBox1.SelectedIndex; DataSet dsProd = new DataSet(); daProd.Fill(dsProd, "Products"); comboBox2.DataSource = dsProd.Tables["Products"]; comboBox2.DisplayMember = "ProductName"; comboBox2.ValueMember = "ProductID"; } }

dont go for dataview when u are able to do the same thing with ur code. ------------------------------------ i want to update my second combo box based on the choice on the first combobox. what is the simplest way to do this? i had my first combobox works. ok.. so far, this is my code for the 1st combobox using (SqlConnection conn = new SqlConnection(Properties.Settings.Default.dbConnectionString)) { SqlDataAdapter da = new SqlDataAdapter("SELECT [CategoryName] FROM Categories",conn); DataSet ds = new DataSet(); daCat.Fill(ds,"Categories"); comboBox1.DataSource = ds.Tables["Categories"]; comboBox1.DisplayMember = "CategoryName"; } i don't know how the code for second combobox will start. but the sql will say something like this.. select productname from products where categoryID=combobox1.text ------------------------------------ NOTE THE CHANGES: (SqlConnection conn = new SqlConnection(Properties.Settings.Default.dbConnectionString)) { SqlDataAdapter da = new SqlDataAdapter("SELECT CategoryID, CategoryName FROM Categories",conn); DataSet ds = new DataSet(); daCat.Fill(ds,"Categories"); comboBox1.DataSource = ds.Tables["Categories"]; comboBox1.DisplayMember = "CategoryName"; comboBox1.ValueMember = "CategoryID"; } and then use the code that I showed you previously.

i have read about using dataview.. but i don't know how to translate my code. can u help me? im just new using this.. ty!

i'm just wondering for the combobox1.SelectedValue... the data being fetched is not a primary key. will that be okay? i mean, there is no categoryName in products table but only categoryID here's the table design categories table categoryID(primary) categoryName products table productID(primary) productName categoryID

daProd.SelectCommand.Parameters.Add("@CategoryID", SqlDbType.Int).Value=comboBox1.SelectedIndex; Dont take comboBox1.SelectedIndex, take combobox1.SelectedValue. Also when you initally fill the combobox1, set its valuemember property to "categoryID".

i tried adding this code but nothing shows in my second combobox private void comboBox1_SelectedIndexChanged(object sender, EventArgs e) { using (SqlConnection conn = new SqlConnection(Properties.Settings.Default.dbConnectionString)) { SqlDataAdapter daProd = new SqlDataAdapter("SELECT [ProductID], [ProductName] FROM Products WHERE CategoryID = @CategoryID", conn); daProd.SelectCommand.Parameters.Add("@CategoryID", SqlDbType.Int).Value=comboBox1.SelectedIndex; DataSet dsProd = new DataSet(); daProd.Fill(dsProd, "Products"); comboBox2.DataSource = dsProd.Tables["Products"]; comboBox2.DisplayMember = "ProductName"; comboBox2.ValueMember = "ProductID"; } }

write the code to fill the 2nd combo box in 1st combobox selectedindexchanged event.