Oracle常见操作

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一些常用到的Oracle数据库操作
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1 取出分组之后每组前多少条数据

select * from
(select name,age row_number() over (partition by name order by age desc) rn from table_name)  
where rn <10

2 同组数据合并（数据行转列）

select name,wm_concat(distinct age) from
(select name,age row_number() over (partition by name order by age desc) rn from table_name)  
group by name

3 奇数行

select  name, age
from (select rownum rn, name, age from table_name) where mod(rn, 2) = 1;

4 复制表以及表中数据

create table table_name_new as select * from table_name;
-- table_name_new 表存在
insert into table_name_new select * from table_name;
commit;

5 查询表的全部字段及其个数

select wn_concat(column_name) from user_tab_cols where table_name=upper('表名');
select count(*) from user_tab_columns where table_name=upper('表名')；

6 查询被锁定表及如何解锁释放session
–锁表查询

SQLSELECT object_name, machine, s.sid, s.serial# 
FROM gv$locked_object l, dba_objects o, gv$session s 
WHERE l.object_id　= o.object_id 
AND l.session_id = s.sid; 

–释放SESSION SQL:

--alter system kill session 'sid, serial#'; 
ALTER system kill session '23, 1647';