PL/SQL block to Display

                 Write a PLSQL block to display following

        
    1
  1 2
  1 2 3
  1 2 3 4

Program: 

declare

str varchar2(10):='12345';

begin

for i in 1..4

loop

dbms_output.put_line(substr(str,1,i));

end loop;

end;

/

Output:

           1

1 2

1 2 3

1 2 3 4