Oracle 随笔

update test1 a set name=(select name from test2 b where a.no=b.no and rownum = 1) where
exists(select  /*+ push_subq*/ 1from test2 b where a.no=b.no and rownum = 1);

 select * from dba_tab_col_statistics where table_name='BUSINESSBASICINFO'

select count(0) from BusinessBasicInfo,CorporationMainTable;

       begin
         dbms_stats.gather_table_stats('XY_CORP','BusinessBasicInfo');
         dbms_stats.gather_table_stats(user,'CorporationMainTable');
         end;

select sid,event from v$session_Wait where event not like 'SQL%';
select * from v$session where sid=627;
select segment_name,bytes/1024/1024 from dba_segments where segment_name='BUSINESSBASICINFO';

select * from v$instance;