Oracle IS NULL

The Oracle IS NULL and IS NOT NULL are comparison conditions used to test for nulls.

Oracle IS NULL and IS NOT NULL example

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

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

Declare
a varchar2(25) := 'oracle'; 
message varchar2(100);
Begin
If a Is Null Then 
message := 'No Data Found'; 
ElsIf a Is Not Null Then 
message := a; 
End If;
End;