Link DropDownList, textbox with sql database

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C#

ASP

.NET

i have a dropdown which lists all the items in my database

and i have another texbox which i want it to display the price of the item selected in the dropdown list. how can i do it? should i code inside the textbox or in the dropdownlist? i Tryed to make a code, but i get many errors!

protected void Page_Load(object sender, EventArgs e)
{
	if(!IsPostBack)
	{
		DropDownList1.DataSource = ds; 
		DropDownList1.DataTextField = "ItemName"
		DropDownList1.DataValueField = "Price";
	        DropDownList1.DataBind();
	}
}

protected void DropDownList1_OnSelectedIndexChanged(object sender, EventArgs e)
{
	TextBox1.Text = DropDownList1.SelectedValue;
}