selectintofrom,selectintofrom用法oracle
SQL数据库中select into from和insert into select的区别
最直接的区别,
select
into
from
,
into的表不存在,执行时先创建表在拷贝数据。
insert
into
select,into的表要存在,执行时只插入数据。
存储过程中的select into from是干什么的
into后边应该还有个变量名,into前面也还要带上筛选字段,例如
select count(*) into v_count from dual;
这条语句的意思是查询dual表的所有记录数,将查询结果存入v_count变量中,也就是给变量设值的用法
什么是select into from和insert into select?
select into from 和 insert into select都是用来复制表,两者的主要区别为: select into from 要求目标表不存在,因为在插入时会自动创建。insert into select from 要求目标表存在。
备份表数据: create table emp as select * from scott.emp
还原表数据:insert into emp select * from scott.emp
复制表结构及其数据:
create table table_name_new as select * from table_name_old
只复制表结构:
create table table_name_new as select * from table_name_old where 1=2;
或者:
create table table_name_new like table_name_old
只复制表数据:
如果两个表结构一样:
insert into table_name_new?select * from?table_name_old
如果两个表结构不一样:
insert into table_name_new(column1,column2...)?select?column1,column2...
from?table_name_old pasting