oracle--sql汇总
1、sql汇总
一、重复操作查询
--where条件得distinct systemdicid作为唯一标识
select *
from dmis_zd_systemdic t
WHERE typeid = '06012'
and t.systemdicid in (select min(systemdicid)
from dmis_zd_systemdic
where typeid = '06012'
group by name)
order by orderno;
二、检查表是否存在
select count(tname) from tab where tname = upper('表名');
三、日期函数
--返回当前日期年度的第一天
select trunc(sysdate,'year') from dual;
--返回当前日期月份的第一天
select trunc(sysdate,'month') from dual;
--上月最后一天
select last_day(add_months(sysdate, -1)) from dual;
--给定日期后最近星期几得日期
select next_day(to_date('2009-12-01', 'yyyy-mm-dd'), '星期一') next_day
from dual;
四、同一张表中，根据一个字段更新另一个字段
update (select t.fgenerationtime as ftime, t.fgeneratedateall as str
from dmis_fs_approvebook t
where t.fgenerationtime is not null)
set str = TO_CHAR(ftime, 'yyyy-mm-dd')
where str is null;
五、重复数据查询
select * FROM EMP E
WHERE E.ROWID > (SELECT MIN(X.ROWID)
FROM EMP X
WHERE X.EMP_NO = E.EMP_NO);
六、合并不同表的数据（merge into）
merge into student s
using (select id, name, tel from test001) x
on (s.s_id = x.id)
when matched then
update set s_name = x.name
when not matched then
insert (s_id, s_name, s_age) values (x.id, x.name, x.tel);
commit;
七、查询执行sql（v$sql）
select t.module, t.first_load_time, t.sql_text
from v$sql t
order by first_load_time desc;
2、数据库精度修改处理
-- Create table
/*drop table temp_data;*/
create table temp_data
(
FID VARCHAR2(40) not null,
USEHOURS NUMBER(10) default 0,
FVOLTAGE NUMBER(10) default 0,
INVOLTAGE NUMBER(10) default 0
)
;
alter table TEMP_DATA
add constraint tempfid primary key (FID);
insert into temp_data
select a.fid, a.usehours, a.fvoltage, a.involtage
from dmis_fs_factorymonthdetail a;
update dmis_fs_factorymonthdetail t
set t.usehours = '', t.fvoltage = '', t.involtage = '';
alter table DMIS_FS_FACTORYMONTHDETAIL modify USEHOURS NUMBER(10,1);
alter table DMIS_FS_FACTORYMONTHDETAIL modify FVOLTAGE NUMBER(10,1);
alter table DMIS_FS_FACTORYMONTHDETAIL modify INVOLTAGE NUMBER(10,1);
update (select a.usehours as tusehours,
b.usehours as fusehours,
a.fvoltage as tfvoltage,
b.fvoltage as ffvoltage,
a.involtage as tinvoltage,
b.involtage as finvoltage,
a.fid as ffid,
b.fid as tfid
from dmis_fs_factorymonthdetail a, temp_data b
where a.fid = b.fid) tt
set tt.tusehours = tt.fusehours,
tt.tfvoltage = tt.ffvoltage,
tt.tinvoltage = tt.finvoltage
where ffid = tfid;
drop table temp_data;
commit;
3、恢复drop掉的存储过程
用sys用户登陆，执行如下的查询：
SQL> select text from dba_source as of timestamp to_timestamp('2009-03-06 09:45:00', 'YYYY-MM-DD HH24:MI:SS') where owner='IPRA' and name= 'P_IPACCHECK_NC' order by line;
4、删除某个用户下的对象
--删除某个用户下的对象
set heading off;
set feedback off;
spool c:\dropobj.sql;
prompt --Drop constraint
select 'alter table '||table_name||' drop constraint '||constraint_name||' ;' from user_constraints where constraint_type='R';
prompt --Drop tables
select 'drop table '||table_name ||';' from user_tables;
prompt --Drop view
select 'drop view ' ||view_name||';' from user_views;
prompt --Drop sequence
select