#学习心德
学一个新知识时 先百度百科
# 函数有返回值 return # create or replace function func_calsale(gdid orders.gdid%type) return number as salenum number(20); begin select sum(buynum) into salenum from orders o where o.gdid=gdid; return salenum; end; # @ /opt/my.sql # select func_calsale(2) from dual;
#存放在数据库中，并被隐含执行的存储过程。在 Oracle8i 之前，只允许给予表或者视图的 的 DML 的操作，而从 Oracle8i 开始，不仅可以支持 DML 触发器，也允许给予系统事件和 DDL 的操作 #触发器是在事件发生时隐式地自动运行的PL/SQL程序块，不能接收参数，不能被调用。 #每当一个特定的数据操作语句(insert update delete)在指定的表上发出时, Oracle自动执行触发器中定义的语句序列。
创建表 实现触发器
# create table orderhistory(oid int primary key,sid int,modifydate date, buynum int);
# create sequence seq_oh;
# @ /opt/my.sql
# set serveroutput on
# update orders set buynum=2 where oid=4;
# update orders set buynum=2;
# rollback;
#-- on 绑在表身上
create or replace trigger trig_order_mod
before update on orders
-- for each row 多行更新都触发
for each row
begin
dbms_output.put_line('Hello');
end;
/
创建表2
create table custs(id int primary key,name varchar(20) not null);
create table cards(id int primary key,trantype int,money
number(10,2));
alter table cards add custid int not null;
alter table cards add constraint FK_cust_card foreign key(custid) references custs(id)
#-----------------------------------------------#
#创建序列
create sequence seq_cust;
create sequence seq_card;
@ /opt/my.sql
insert into custs values(seq_cust.nextval,'zs');
commit;
select * from custs;
#-----------------------------------------------#
create or replace trigger trig_bank
after insert on custs
for each row
begin
insert into cards values(seq_card.nextval,1,1,:new.id);
end;
/
#-----------------------------------------------#
desc orderhistory;
create sequence seq_his;
@ /opt/my.sql
select * from orderhistory;
#-----------------------------------------------#
create table myorders(id int primary key, ordid int, status int,starttime datetime, overtime datetime);
create table xyz(id int primary key, dt timestamp );
insert into xyz values(1,sysdate);
commit;
select * from xyz;
alter table xyz modify dt timestamp(2);
delete from xyz;
commit;
#-----------------------------------------------#
oracle 时间戳转换日期
select to_date(dt,'yyyy-MM-dd hh24:mi:ss') from xyz;
select to_char(dt,'YYYY-MM-DD hh24:mi:ss') from xyz;
select to_date(to_char(dt,'YYYY-MM-DD hh24:mi:ss')) from xyz;
select to_timestamp('9999-12-31 23:59:59','YYYY-MM-DD hh24:mi:ss') from dual;
#-----------------------------------------------#
create table myorders(id int primary key,orderid int, status int ,starttime timestamp(0),overtime timestamp(0));
desc myorders;
#-----------------------------------------------#
select * from xyz where to_char(dt,'YYYY-MM-DD')='2022-06-24';
#-----------------------------------------------#
开始测试
@ /opt/my.sql
desc myorders;
insert into myorders values(1,1,1,sysdate,to_timestamp('9999-12-31 1:0:0','YYYY-MM-DD hh:mi:ss'));
rollback;
######## 显示输出
@ /opt/my.sql
select * from myorders;
insert into myorders values(1,1,1,sysdate,to_timestamp('9999-12-31 1:0:0','YYYY-MM-DD hh:mi:ss'));
insert into myorders values(2,1,2,sysdate,to_timestamp('9999-12-31 1:0:0','YYYY-MM-DD hh:mi:ss'));
select * from myorders;
#-----------------------------------------------#
create or replace trigger trig_myorder
before insert on myorders
for each row
begin
update myorders set overtime=sysdate where ORDERID=:new.orderid
and to_char(overtime,'YYYY-MM-DD')='9999-12-31';
-- dbms_output.put_line(:new)
end;
/
######## 上面是vs代码
删除触发器
create or replace procedure proc_myorder
(ordid myorders.orderid%type,ordstatu myorders.status%type)
as
begin
update myorders set ovetime=sysdate where ORDERID=ordid
and to_char(ovetime,'YYYY-MM-DD')='9999-12-31';
insert into myorders values(seq_mo.nextval,ordid,ordstatu
,sysdate,to_timestamp('9999-12-31 1:0:0','YYYY-MM-DD hh:mi:ss'));
end;
/
#-----------------------------------------------#
drop trigger trig_myorder;
delete from myorders;
#给数据分区 #加快查询效率 #方法如下 传统表分区 2.1.1范围分区range2.1.2 列表分区list2.1.3 哈希分区hash2.1.4 复合分区 range + list or hash2.2 11g 新特性分区 2.1.1引用分区 reference 2.1.2 间隔分区interval
创建分区表
drop table stus; create table stus(stid int primary key,name varchar(20),age int) partition by range(age)( partition p1 values less than(20) tablespace mydemo, partition p2 values less than (50) tablespace mydemo, partition p3 values less than (maxvalue) tablespace mydemo);#测试
insert into stus values(1,'zs',18); insert into stus values(2,'ls',19); select * from stus partition(p1); select * from stus partition(p2); select * from stus partition(p1,p2);
删除表
drop table stus;
create table stus (id int primary key,name varchar(20),age number) partition by hash(name)( partition p1 tablespace mydemo, partition p2 tablespace mydemo, partition p3 tablespace mydemo ); insert into stus values(1,'zs',18); insert into stus values(2,'zsf',100); select * from stus partition(p1); select * from stus partition(p2); select * from stus partition(p3); insert into stus values(3,'lisi',22); insert into stus values(4,'lisiguang',1221); select * from stus partition(p3);
存在热点问题
用函数再次hash法 加盐？ 随机值做尾巴
解决代码
create table stus1(id int primary key,name varchar(20),age int,hashname varchar(30)) partition by hash(hashname)( partition p1 tablespace mydemo, partition p2 tablespace mydemo, partition p3 tablespace mydemo ); insert into stus1 values(1,'zs',10,trunc(dbms_random.value(1,1000))||'zs');
create table addrs(id int primary key,name varchar(20),subid int); insert into addrs values(1,'chian',0); insert into addrs values(2,'jiangsu',1); insert into addrs values(3,'zhejiang',1); insert into addrs values(4,'nanjing',2); insert into addrs values(5,'xuzhou',2); insert into addrs values(6,'hangzhou',3); insert into addrs values(7,'jiaxing',3);
输一个名字显示关联的名字
--创建函数
create or replace function fun_linked(city addrs.name%type) return varchar
as
--定义变量
res varchar(100);
nm varchar(20);
suid varchar(10);
begin
--res接收到传入的city
res:=city;
select name,subid into nm,suid from addrs where name=city;
-- 开始循环 ==0直接返回
while (suid != 0) loop
select name,subid into nm,suid from addrs where id=suid;
-- ==后面的res是之前的城市 nm是后面查出的城市
res:= res || ',' || nm ;
end loop;
--返回res数据里面有一个或者多个city
return res;
end;
/
#-----------------------------------------------#
@ /opt/my.sql
select fun_linked('xuzhou') from dual;
select * from addrs start with id=1 connect by id=prior subid; select * from addrs start with id=2 connect by prior id=subid;
create or replace function fucs(city addrs.name%type)return
varchar
as
flag varchar(100);
aname varchar(20);
asubid varchar(20);
begin
flag:=city;
select name,subid into aname,asubid
from addrs
where name=city;
while(asubid !=0) loop
select name,subid into aname,asubid
from addrs
where id=asubid;
flag:=flag || ' +++++ ' || aname
end loop;
return flag;
end;
/