oracle join连接

1.默认全连接

create table tab_big  as select * from dba_objects where rownum<=30000;
create table tab_small  as select * from dba_objects where rownum<=10;
set autotrace traceonly
set linesize 1000
set timing on 
select count(*) from tab_big,tab_small   ;  //两个表的顺序与查询速度无关
select count(*) from tab_small,tab_big   ;

 select * from t1,t2 where t1.object_id=29 and t2.data_id>8;//查询条件顺序与查询速度无关
 select * from t1,t2 where t2.data_id>8 and t1.object_id=29