lishankang

摘要： 第一次执行：drop table t purge;create table t as select * from dba_objects;set linesize 1000set autotrace on set timing onselect count(*) from tSQL> create table t as select * from dba_objects;表已创建。SQL> set timing on;SQL> set linesize 1000;SQL> set autotrace on;SQL> select count(*) from t; 阅读全文