how to selected combo box item name C#

Question

how to selected combobox item name show in gridview and ID save in database

and same work on Update Queery in windows application c#

 

 

 // Insert Queery

cmd = new SqlCommand("insert into Product(Name,Description,Tax_ID,Unit_ID) values(@Name,@Description,@Tax_ID,@Unit_ID)", con);

con.Open();

cmd.Parameters.AddWithValue("@Name", txtName.Text);

cmd.Parameters.AddWithValue("@Description", txtdec.Text);

cmd.Parameters.AddWithValue("@Tax_ID", comboBoxtax.Text);

cmd.Parameters.AddWithValue("@Unit_ID", comboBoxunit.Text);

 

 

 // Update Queery

cmd = new SqlCommand("update Product set Name=@Name,Description=@Description,Tax_ID=@Tax_ID,Unit_ID=@Unit_ID where Product_ID=@id", con);

con.Open();

cmd.Parameters.AddWithValue("@id", Product_ID);

cmd.Parameters.AddWithValue("@Name", txtName.Text);

cmd.Parameters.AddWithValue("@Description", txtdec.Text);

cmd.Parameters.AddWithValue("@Tax_ID", comboBoxtax.Text);

cmd.Parameters.AddWithValue("@Unit_ID", comboBoxunit.Text);