Question

i am working on VC#.net

i have connected my combox with my database

when the combox change’s the value then my textbox should show the corresponding value
in the textbox

Answer 1

You need to subscribe to SelectionChanged event of your ComboBox, then in eventhandler method use the following

if (comboBox.SelectedItem == null) 
{
   textBox.Text = string.Empty; //or any default value
   return;
}
textBox.Text = comboBox.SelectedValue.ToString();