NULL Examples

Example 1

Select *
  From invoices i
Where i.printed IS NULL ;

Example 2

Select *
  From invoices i
Where i.printed IS NOT NULL ;


Example 3

Declare
   a = 'oracle';
Begin
  If a Is Null Then
    message := 'No Data Found';
  ElsIf a Is Not Null Then
    message := a;
  End If;
End;