declare
msg varchar2(100);
num integer :=1;
begin
  
msg :=‘a‘;
case msg 
  when ‘a‘ then 
dbms_output.put_line(‘1‘);
else 
  dbms_output.put_line(‘3‘);
end case ;
<<bloop>>
loop
  
num:=num+1;
  dbms_output.put_line(num);
if num>10 then
  
exit bloop;
end if ;
end loop;
for inx in 1..20 loop
  
num:=num+1;
  dbms_output.put_line(num);
end loop;
end;
原文:http://www.cnblogs.com/tiancai/p/6860477.html