Форматировать DropDownList.TextValue

My stored procedure is like this

SELECT Id, StudentName
FROM xyz

I have a drop down list in asp.net, which I am loading as :

ddlA.DataSource = // Some source
ddlA.DataTextField = "Id" + " -" + "StudentName";
ddlA.DataValueField = "Id";
ddlA.DataBind();
ddlA.Items.Insert(0, new ListItem(" Select one", "0"));

But at the Databind() statement, I am getting this error:

System.Web.HttpException: DataBinding: 'System.Data.DataRowView' does not contain a property with the name 'Id-StudentName'.

In text part of the dropdown list, I want to display the concatenated value of Id - StudentName.

How can I do it?