oracle 使用绑定变量极大的提升性能

初始化操作

SQL> alter system flush shared_pool;
SQL> set timing on;

1. 未使用绑定变量的时候代码如下

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 ..
          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)/,)||'seconds...');
end;

执行结果：
    PL/SQL procedure successfully completed
    Executed in 14.196 secondsed

2. 使用了绑定变量的方式执行

 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 ..
           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)/,)||'seconds...');
 end;

 执行结果：
     PL/SQL procedure successfully completed
     Executed in 0.141 seconds