绑定变量与应编码的不同

declare
 type rc is ref cursor;
 l_rc rc;
l_dummy all_objects.object_name%type;
l_start number default dbms_utility.get_time;
begin
  for i in 1 .. 1000
  loop
    open l_rc for 'select object_name from all_objects where object_id =' ||i;
    fetch l_rc into l_dummy;
    close l_rc;
  end loop;
dbms_output.put_line(round((dbms_utility.get_time-l_start)/100,2)||'seconds...');
end;

 

运行花费时间：19.72seconds...

 

declare
type rc is ref cursor;
l_rc rc;
l_dummy all_objects.object_name%type;
l_start number default dbms_utility.get_time;
begin
  for i in 1 .. 1000
  loop
    open l_rc for 'select object_name from all_objects where object_id = :x'
    using i;   
    fetch l_rc into l_dummy;
    close l_rc;
  end loop;
dbms_output.put_line(round((dbms_utility.get_time-l_start)/100,2)||'seconds...');
end;

 

行花费时间：0.187 seconds

 

declare
 type rc is ref cursor;
 l_rc rc;
l_dummy all_objects.object_name%type;
l_start number default dbms_utility.get_time;
begin
  for i in 1 .. 1000
  loop
    open l_rc for select object_name from all_objects where object_id =i;
    fetch l_rc into l_dummy;
    close l_rc;
  end loop;
dbms_output.put_line(round((dbms_utility.get_time-l_start)/100,2)||'seconds...');
end;

 

运行花费时间：0.19seconds...