分享知識-快樂自己:Oracle SQL語法彙總
阿新 • • 發佈:2018-11-09
--刪除重複值-保留重複值最大的編號
delete from emp where rowid in(
select rowid from emp where rowid not in(
select max(rowid) rd from emp group by empname)
)
--去重複查詢
select distinct empname from emp
--查詢重複值以外的所有資訊
select * from emp where empname in(select empname from emp group by empname having count(empname)=1)
--三層巢狀實現分頁
select * from
(
select emp.*,rownum rn
from emp
where rownum<=(3*3)
) where rn>=(3-1)*3+1
--舊錶備份新表
create table emp1 as select * from emp
--並集,查詢兩張表不重複的值
select * from emp
union
select * from emp1
--並集,查詢兩張表所有 及 重複值
select * from emp
union all
select * from emp1
--交集查詢兩張表共同存在的值
select * from emp
INTERSECT
select * from emp1
--減集 emp1 - emp 剩餘的資訊
select * from emp1
MINUS
select * from emp
--查看回收站的表
SELECT * FROM RECYCLEBIN;
--根據查詢的資訊還原表(恢復表時,索引和表資料等相關資訊都會自動恢復)
flashback table '需要恢復的表名(original_name)' to before drop;