var query = from p in db.table1
                   where !db.table2.Any(q=> q.id== p.id)
                   select p;

this.Repeater1.DataSource = query;
this.Repeater1.DataBind();

------解决方案--------------------
var rs =from order in db.table1.Include("table2")
                            where(条件)
                            select order;
                           
Repeater.DataSource = rs;
Repeater.DataBind();

------解决方案--------------------
linq to sql?


var query=db.Table1.Contact(db.Table2).ToList();
this.Repeater1.DataSource = query;
this.Repeater1.DataBind();



------解决方案--------------------
var news = bn.SelectRecordAll();//拿到table1数据
 var promo = bp.SelectRecordAll();//拿到table2数据

 Repeater1.DataSource = news.Union(promo).ToList();
 Repeater1.DataBind();

------解决方案--------------------
探讨


不会用，db.table1.Contact(db.table2).ToList();这样子 
报错 
说不包含 Contact()的定义