Dropdown in Gridview

for adding a dropdown in gridview refer:
http://highoncoding.com/Articles/169_DropDownList_Inside_GridView__Method_1_.aspx[^]

and for having the the items in the secodd dropdown depending on selection of first dropdown u should use SelectedIndexChanged event of first dropdown, as:

protected void ddlProduct_SelectedIndexChanged(object sender, EventArgs e)
   {       
       int product_id= Convert.ToInt32(ddlProduct.SelectedValue);
       ds = belobj.GetDataSet("GetPrice", "PRODUCT_ID=" + product_id);//get the values for price from database
       ddlPrice.DataSource = ds.Tables[0];
      
       ddlPrice.DataBind();
   }

You really should be doing this in an Object Oriented manner. You should have a class called Product. Then when your user opens the billing form, you should populate the Product ComboBox with a List of the Products. When the user selects a Product from the Combo, the retail price and everything is automatically included as part of the class, and so you could populate a Textbox with the retail price and maybe another with the available quantity, then the user can just select a quantity with a numeric up down control and click an addtobill button which then includes the selected item and quantity in the DataGridView. Then you couls have a saveandprint button which saves the order to the database and prints a receipt/invoice.

Hope this helps

You need to add selectedindexchanged event of first dropdown and from there you can dynamically change the second dropdown content..
hope it'll help you..