Here I blogged about setting errors in the data set. In this post I will just show you what it could look like in a windows forms application. (Maybe I should have done this earlier.)

In this example I have used the ErrorProvider control. The only steps necessary to get this functionality is to drag the control onto your form, set the DataSource property to your data set and DataMember to the name of your table. It is also necessary to set the ContainerControl property to your form and I usually sets the BlinkStyle property to NeverBlink.