oracle 学习笔记

1.oracle查询结果去除重复项

SELECT DISTINCT * FROM TABLE_NAME

2.合并查询结果

select id,name from wg_person
union
select id,name from wg_superUsers
从person表和superuser表中查询到的结果合并

3.递归查询

START WITH PID = :id CONNECT BY PRIOR ID = PID
一般和union语句结合使用:
START WITH PID = :id CONNECT BY PRIOR ID = PID 
union
select id from wg_depart where id=:id

4.新安装的数据库,需要设置nls_lang环境变量

变量名:NLS_LANG
值:AMERICAN_AMERICA.ZHS16GBK

5.oracle从dmp文件导入数据

$imp 'aichannel/aichannel@192.168.1.36/orcl as dba' full=y file=路径\文件名.dmp ignore=y
imp userid=username/password@192.168.1.36/orcl file=路径\文件名.dmp full=y

6.oracle从dmp文件导出数据

$exp username/password@orcl file=/path/db.sql log=/path/dblog.log owner=username

7.pl/sql登录本地数据库失败问题

可能原因:
1.服务没启动,需要启动的有两个,OracleOraDb11g_home1TNSListener和OracleServiceOrcl
2.把需要连接的数据库名字改为127.0.0.1/orcl

8.oracle修改最大连接数,修改内存占用

show parameter processes;
show parameter sessions;
alter system set processes=2000 scope=spfile;
alter system set sessions=2200 scope=spfile;
show parameter memory;
alter system set memory_target=2688M scope=spfile;
alter system set memory_max_target=2688M scope=spfile;

9.oracle创建用户,并赋权限

create user uname identified by pass
grant dba,connect to zyl

10.oracle导入dmp文件

imp userName/password FILE=文件路径.dmp FULL=Y

11.plsql提示:ORA-04098:trigger 'XXX.XXX' is invalid and failed re-falidation 错误

应该是在表上建了触发器,在Triggers中找到并禁用就能插入数据了

12.复杂update语句

update person t set t.url=replace(url,'aaa','bbb') where t.url is not null  // 把url中的aaa替换成bbb

13.批量插入查询到的数据到新表中

insert into tb_workgroupdispatch a(id,departid,workgroupid)
select rownum,w.jigouid,w.id from wggl_workgroup w where 条件;

14.oracle生成uuid方法

create or replace function fun_get_uuid
return varchar
is
guid varchar (50);
begin
	guid := lower(rawtohex(sys_guid()));
	return substr(guid,1,8)||'-'||substr(guid,9,4)||'-'||substr(guid,13,4)||'-'||substr(guid,17,4)||'-'||substr(guid,21,12);
end fun_get_uuid;

select fun_get_uuid from dual;
update tb_person t set t.uuid=(select fun_get_uuid from dual) where t.id=1;--修改id=1的uuid

15.循环更新表中所有记录

create or replace procedure pro_set_person_uuid 
is
  i number;
begin
  i:=15000;
  --select count(1) into i from tb_person p where p.uuid is null;分批执行,如果太多,容易内存溢出
  while i>0 
  loop
      i:=i-1;
      update tb_person t set t.uuid=(select fun_get_uuid from dual) where t.uuid is null and rownum=1;
  end loop;
end;

begin
	pro_set_person_uuid;
end;