oracle语法学习

1.备份表

create table bd_psndoc_temp as select * from bd_psndoc

2.还原表

drop table bd_psndoc;
create table bd_psndoc as select * from bd_psndoc_temp

3.查询表的前5条记录

select * from bd_psndoc_temp where rownum<=5

4.从一个表中复制所有的列插入到另一个已存在的表中

insert into bd_psndoc_temp select * from bd_psndoc

5.oracle函数

select avg(sumnum),count(*),max(sumnum),min(sumnum),sum(sumnum) from kf_kfckd