下雪了，先是小朵小朵的雪花，柳絮般轻轻地飘扬；然后越下越大，一阵紧似一阵。
组合集总计： group by with rollup/cube
grouping sets
子查询按执行方式分：标准子查询、关联子查询
标准子查询：嵌套子查询
标量值查询
case with then
使用exits查询
select user_id,user_name from tb_001 tb
where [not] exists (select 'x'
from tb_001
where manager_id=tb.user_id )
关联更新
update table1 alias1
set column=(select expression
from table2 alias2
where alias1.column=alias2.column);
关联删除
delete from table1 alias11
where column operator
(select expression
from table2 alias2
where alias1.column=alias2.column);
分层结构
分层检索
select [level],column,expr...
from table
[where with condition(s)]
[connect by prior condition(s)]
connect by prior column1=column2
top down:
colum1=parentkey
column2=childkey
bottom up:
column1=childkey
column2=parentkey 插入语句insert statement
insert into table[(column[,column...])]
values(value[,value...])
修改语句update statement
update table
set column=value[,column=value,...]
[where condition]; 多表插入语句(Multitable Insert Statements) insert [all] [conditional_insert_clause]
[insert_into_cause values_clause](subquery)
conditional_insert_clause
[all][first]
[when condition then][insert_into_clause values_clause]
[else][insert_into+clause values_clause]
列：
intsert all
into tb_user values(id,uid,upwd)
into tb_user_info values(id,name,sex,age)
select id,uid,upwd,name,sex,age
from tb_u_10
where id>10000;
待条件的多行插入
insert all
when id>11000 then
into tb_user values(id,uid,upwd)
when age>40 then
into tb_user_info values(id,name,sex,age)
select id,uid,upwd,name,sex,age
from tb_u_10
where id>10000;
insert first
when conditional then
into ...
when conditional then
into ...
else
into...
select...
创建索引
cretate table t_10
(id number(6) not null primary key using index (create index index1 on t_10(id)),
name varchar2(50));
查询索引
select * from user_indexes;
以上就是Oracle学习笔记(五)。心，可以超越困难、突破阻挠；心，可以粉碎障碍；心，最终必会达到你的期望。然而，成功的的障碍，往往又是你的心！是你面对不可能完成的高度时，心为自己设定的瓶颈。更多关于Oracle学习笔记(五)请关注haodaima.com其它相关文章！