Oracle SQL经典荟萃

 

Oracle SQL经典荟萃

将自己学习，工作中整理的一些经典SQL和大家分享一下。注意，在Oracle 9i中tiger账户默认是开启的，后续版本则改变了策略~同时，关于sql优化尤其是hint的使用，这里不做分享，具体可以查阅民间流传的50大招~

 

-- toy sql
alter user scott account unlock;
select ename,sal*12 as "annual sal" from emp;
--注意：""保持了字段名的小写状态
select ename,sal*12 + comm from emp;
select job||'KaK''a' from emp;
select ename,sal*12 + nvl(comm,0) from emp;
--注意：任何含有空值的数学表达式，计算结果都是空值;字符串连接过程中，单引号使用'转义
select distinct deptno,job from emp;
--distinct deptno,job组合唯一
select ename,sal from emp where deptno <>10;
--Oracle中日期型处理技巧。1.1-1月-1982 2。date'1982-01-01'
select ename,hiredate from emp where hiredate>'1-1月-1982';
select ename,hiredate from emp where hiredate>to_date('1982-1-1','yyyy-mm-dd');
--SQL中不等于的方法
select ename,sal from emp where sal between 800 and 1500;
select ename,sal from emp where sal >=800 and sal<=1500;
--指定$为转义字符
select ename from emp where ename like '%$%%' escape '$';

select lower(ename) from emp;
select upper(ename) from emp;
select substr(ename,1,3) from emp;
select * from emp where length(ename)=5;
select upper(substr(ename,1,1)) from emp || select lower(substr(ename,2,length(ename)-1))from emp;
select chr(65) from dual;
select ascii('A') from dual;
select round(25.656,-1) from dual;
--L,本地货币符号，C，国际货币符号
select to_char(sal,'$999,999.999')from emp;
select to_char(sal,'L999,999.999')from emp;
select to_char(sal,'L000,000.000')from emp;
select to_char(hiredate,'YYYY-MM-MM HH24:MI:SS') from emp;
select ename,hiredate from emp where hiredate > to_date('1981-02-20 12:00:00','YYYY-MM-DD HH24:MI:SS');
select sal from emp where sal>to_number('$1,250.00','$99,999.99');
select replace(ename,'a','A') from emp;
select sys_context('USERENV','db_name') from dual;
select sys_context('USERENV','current_schema') from dual;
--用户和方案的关系:一一对应,Oracle是以方案的方式管理数据对象的，用户名和方案名相同

select deptno,job,max(sal) as max_sal from emp group by deptno,job;
--按照两个字段进行分组
select deptno,round(avg(sal),2) from emp group by deptno;
--注意：出现在select列表中的字段，如果没有出现在组函数里，那么必需出现在group by语句里！
--分组函数只能出现在选择列表，having，order by子句中！
select ename,deptno from emp where sal in (select max(sal)from emp group by deptno);
select ename from emp where sal in --= (select max(sal) from emp);
select deptno,max(sal) from emp group by deptno;
select deptno,round(avg(sal)) from emp group by deptno having avg(sal)>2000 order by deptno;
--注意：where是对单条语句过滤，而having是对分组进行过滤！
select ename,deptno from emp order by deptno desc;
select avg(sal) from emp where sal>1200 group by deptno having avg(sal) >1500 order by avg(sal) desc;
select * from product_component_version;
select ename,sal from emp where sal > (select avg(sal) from emp);

--每个部门中薪水最高的人
select ename,deptno,sal from emp where sal in (select max(sal) from emp group by deptno);
--仔细分析上述写法，在大数据量条件下，会出现偏差
select ename,sal,emp.deptno from emp join (select max(sal) as max_sal,deptno from emp group by deptno) t on(emp.sal = t.max_sal and emp.deptno = t.deptno);

select t1.ename as clerk,t2.ename as boss from emp t1 ,emp t2 where t1.mgr = t2.empno;
select t1.ename as clerk,t2.ename as boss from emp t1 join emp t2 on (t1.mgr = t2.empno);

select t1.ename as clerk,t2.ename as boss from emp t1 left outer join emp t2 on (t1.mgr = t2.empno);
select ename,dname from emp right outer join dept on (emp.deptno = dept.deptno);
select ename,dname,grade from emp e,dept d,salgrade s where e.deptno = d.deptno and e.sal between s.losal and s.hisal and job <> 'CLERK';
--超强震撼，99语法将连接条件与数据过滤条件分离，仔细品味吧！
select ename,dname,grade from emp join dept on ( emp.deptno = dept.deptno ) join salgrade on(emp.sal between salgrade.losal and salgrade.hisal) where ename not like '_A%';

--SQL 99与SQL 92的区别 : Where 语句后只跟数据过滤条件 ！
select ename,dname from emp,dept;
select ename,dname from emp cross join dept;
-- 等值连接
select ename,dname from emp,dept where emp.deptno = dept.deptno;
select ename,dname from emp join dept on ( emp.deptno = dept.deptno );
select ename,dname from emp join dept using (deptno);
--部门平均薪水的等级
select deptno,avg_sal,grade from(select deptno,avg(sal) as avg_sal from emp group by deptno) t join salgrade s on(t.avg_sal between s.losal and s.hisal);
--部门平均的薪水等级
select deptno,avg(grade) from(select deptno,ename,grade from emp join salgrade on(emp.sal between salgrade.losal and salgrade.hisal)) group by deptno;
--雇员中谁是经理人
select ename from emp where empno in (select distinct mgr from emp);
--不用聚集函数求最高薪水
select distinct sal from emp where sal not in(select distinct e1.sal from emp e1 join emp e2 on(e1.sal < e2.sal));
--平均薪水最高的部门的部门编号
select deptno,avg_sal from (select deptno,avg(sal) avg_sal from emp group by deptno)
where avg_sal =(select max(avg_sal) from (select deptno,avg(sal) avg_sal from emp group by deptno));
--同样的例子，使用聚集函数嵌套！
select deptno,avg_sal from (select deptno,avg(sal) avg_sal from emp group by deptno)
where avg_sal =(select max(avg(sal)) from emp group by deptno);
--平均薪水最高的部门的部门名称
select dname from dept where deptno = (select deptno from (select deptno,avg(sal) avg_sal from emp group by deptno)
where avg_sal =(select max(avg_sal)
from (select deptno,avg(sal) avg_sal from emp group by deptno)));
--平均薪水等级最低的部门的部门名称
select t1.deptno,dname,avg_sal,grade from
(
   select deptno,grade,avg_sal from
     (
        select deptno,avg(sal) as avg_sal from emp group by deptno
     ) t join salgrade s on
         (
            t.avg_sal between s.losal and s.hisal
          )
) t1 join dept on
    (
       t1.deptno = dept.deptno
    ) where t1.grade =
      (
           select min(grade) from
            (
                select deptno,avg_sal,grade from
                 (
                   select deptno,avg(sal) avg_sal from emp group by deptno
                 ) t join salgrade s on
                   (
                     t.avg_sal between s.losal and s.hisal
                   )
           )
        );
--显示高于自己部门平均工资的员工信息
select t1.ename,t1.sal,t1.deptno,t2.avg_sal from emp t1,(select deptno,avg(sal) avg_sal from emp group by deptno) t2 where t1.deptno = t2.deptno and t1.sal > t2.avg_sal;
--另类做法
--1.创建视图
create view v$dept_avg_sal_info as
select deptno,grade,avg_sal from
     (
        select deptno,avg(sal) as avg_sal from emp group by deptno
     ) t join salgrade s on
         (
            t.avg_sal between s.losal and s.hisal
          );
--2.使用刚创建的视图进行查询
select t1.deptno,dname,avg_sal,grade from
(
   select deptno,grade,avg_sal from
     (
        select deptno,avg(sal) as avg_sal from emp group by deptno
     ) t join salgrade s on
         (
            t.avg_sal between s.losal and s.hisal
          )
) t1 join dept on
    (
       t1.deptno = dept.deptno
    ) where t1.grade =
      (
           select min(grade) from v$dept_avg_sal_info
      );
--比普通员工的最高薪水还高的经理人名称
select ename from emp where empno in
(
    select distinct mgr from emp where mgr is not null
)
  and sal >
    (
      select max(sal) from emp where empno not in(select distinct mgr from emp where mgr is not null)
     );
--备份表
create table emp2 as select * from emp;
grant dba to scott;

grant create table,create view to scott;

--逻辑备份
--1. exp
--2. create user ** identified by ** default tablespace users quota 10M on users
--3. grant create session,create table,create view to **
--4. imp
--另类insert
insert into emp2 select * from emp;

select ename from (select rownum r ,ename from emp) where r > 10;
--薪水最高的前5名雇员
--错误的写法！（错误原因：先取出前5个，才排序）
select ename,sal from emp where rownum <=5 order by sal desc;
--正确的写法！
select ename,sal from (select ename,sal from emp order by sal desc) where rownum <=5;

--薪水最高的第6个到第10个人
select ename,sal,rownum r from (select ename,sal,rownum r from(select ename,sal from emp order by sal desc))where r<=10 and r>=6;
--hibernate 写法
select * from ( select row_.*, rownum rownum_ from ( select ename,sal from emp order by sal desc) row_ where rownum <= 10) where rownum_ >=6;
--显示比部门30的所有员工的工资都高的员工姓名，工资和部门号
select ename,sal,deptno from emp where sal> all--any (select sal from emp where deptno=30);
select ename,sal,deptno from emp where sal >(select max(sal) from emp where deptno =30);--效率高
--查询与SMITH的部门和岗位完全相同的所有员工
select * from emp where (deptno,job)=(select deptno,job from emp where ename='SMITH');
--希望SCOTT员工的岗位，工资，津贴与SMITH员工一样
update emp set(job,sal,comm)=(select job,sal,comm from emp where ename='SMITH') where ename='SCOTT';
--查询8个月前入职的员工
select * from emp where sysdate>add_months(hiredate,8);
--显示满10个月服务年限的员工姓名和受雇日期
select ename,hiredate from emp where sysdate>=add_months(hiredate,12*10);
--显示每个雇员入职天数
select ename,floor(sysdate-hiredate) as '入职天数' from emp;
--各月倒数第3天受雇的员工
select * from emp where last_day(hiredate)-2=hiredate;
--SQL注入漏洞
select * from emp where empno='7369' and ename='SMITH' or 1='1';
--MS SQL中起作用
select * from emp where empno='7369';delete from emp;--'and ename='SMITH';
--查询员工信息（包括其直接上司）
select e1.empno,e1.ename,e1.mgr,e2.ename from emp e1 left join emp e2 on e1.mgr=e2.empno
select e1.empno,e1.ename,e1.mgr,(select e2.ename from emp e2 where e2.empno = e1.mgr) as mgrname from emp e1
--查询员工7902的所有上级
select empno,ename,level from emp connect by empno = PRIOR mgr start with empno = 7902;
--查询员工7902的所有下级
select empno,ename,level from emp connect by PRIOR empno = mgr start with empno = 7902;
--使用rowid删除重复项，保留rowid最大一项，模式如：
select rowid,t.product_type,t.order_datetime from tb_order_view t where rowid != (select max(rowid)from tb_order_view b where b.product_type = t.product_type and b.order_datetime = t.order_datetime)
--case...when...then
select e1.empno,
       e1.ename,
       e1.job,
       e1.hiredate,
       e1.sal,
       case
         when e1.sal < 1000 then
          '低'
         else
          (case
            when e1.sal <= 3000 then
             '中'
            else
             '高'
          end)
       end as grade
  from emp e1

select count(case when sal<1000 then 1 else null end)low,
       count(case when sal between 1000 and 3000 then 1 else null end)mid,
       count(case when sal >3000 then 1 else null end) high from emp


--数据库完整性实现方式之-约束（5种）,包括列级定义，表级定义
--1.非空 2.唯一 3.主键 4.外键 5.Check
create table stu(
id number(6),
name varchar2(20) constraint stu_name_nn--自定义约束名字 not null,
sex char(2) default '男' check(sex in('男','女')),
age number(3) check(age>0),
sdate date,
grade number(2) default 1,
class number(4) --references class(id),
email varchar2(50),
constraint stu_fk foreign key (class) references class(id),
constraint stu_id_pk primary key(id),
constraint stu_unique unique(email,name)
);
create table class(
id number(4) primary key,
name varchar2(20)
);
alter table class modify name not null;
alter table class add constraint nameUnique unique(name);
select constraint_name,constraint_type,status,validated from user_constraints where table_name='emp';
select column_name,position from user_cons_columns where constraint_name='nameUnique';
--null值，数据库不认为是重复值

--表修改
alter table stu add(addr varchar2(100));
alter table stu drop(addr);
alter table stu drop column addr;
rename stu to student;--修改表名字
alter table stu modify(addr varchar2(50));--修改字段长度或类型（空表）
--约束条件操作
alter table stu drop constraint stu_fk;
alter table stu add constraint stu_fk foreign key (class) references class(id);

--数据字典表
desc user_tables;
select table_name from user_tables;
select view_name from user_views;
select constraint_name from user_constraints;
select constraint_name,table_name from user_constraints;

desc dictionary;
select table_name from dictionary;

--索引与视图(主键约束和唯一约束)
create index index_stu_email on stu(email);--也可以设置复合索引，注意顺序不同（区分度高的字段放后面），索引不同，索引的层次不要超过4层。
drop index index_stu_email;
select index_name from user_indexes;
select view_name from user_views;
--索引的缺点。1.系统需要为索引开辟大约为表存储容量1.2倍的空间（硬盘空间和内存空间）。2.更新数据时，系统需要额外的时间来对索引进行同步更新。
select index_name,index_type from user_indexes where table_name='emp';
select table_name,column_name from user_id_columns where index_name='emp';

create sequence seq;
select seq.nextval from dual;

create view v$view_table as select M.column_name FieldName from (select * from user_tab_columns where upper(Table_name) = upper('BLB')) M left join user_col_comments A ON M.COLUMN_NAME=A.COLUMN_NAME and M.Table_Name = A.Table_Name
left join (select a.table_name,b.column_name from user_constraints a, user_cons_columns b where a.constraint_name=b.constraint_name and upper(a.table_name)=upper('BLB') and a.constraint_type='P') B ON M.Table_Name = B.TABLE_NAME and M.COLUMN_NAME=B.COLUMN_NAME order by M.column_id;

insert into [用户表](id) select * from v$view;

create or replace procedure insert_ID is
begin
  for i in 1..196 loop
      insert into lcqkbt(id) values(seq.nextval);
  end loop;
  commit;
end;

alter database datafile '' resize 100M;

--dba daily work
create table errorlog(
   id number primary key,
   errcode number,
   errmsg varchar2(1024),
   errdate date
);
create sequence seq_errorlog_id start with 1 increment by 1;
declare
  v_deptno dept.deptno%type :=10;
  v_errcode number;
  v_errmsg varchar2(1024);
begin
  delete from dept where deptno = v_deptno;
  commit;
exception
  when others then
       rollback;
              v_errcode :=SQLCODE;
              v_errmsg:=SQLERRM;
       insert into errorlog values(seq_errorlog_id.nextval,v_errcode,v_errmsg,sysdate);
       commit;
end;

declare
  cursor c is
         select * from emp;
  v_emp c%rowtype;
begin
  open c;
  loop
       fetch c into v_emp;
       exit when(c%notfound);
       dbms_output.put_line(v_emp.ename);
  end loop;
  close c;
end;

declare
  cursor c is
         select * from emp;
  v_emp c%rowtype;
begin
  open c;
       fetch c into v_emp;
       while(c%found) loop
       dbms_output.put_line(v_emp.ename);
       fetch c into v_emp;
  end loop;
  close c;
end;

declare
  cursor c is
         select * from emp;
begin
    for v_emp in c loop
       dbms_output.put_line(v_emp.ename);
  end loop;
end;

update dept set deptno = 99 where deptno = 10;
create or replace trigger cascadeUpdate
   after update on dept
   for each row
begin
   update emp set deptno = :NEW.deptno where deptno=:OLD.deptno;
end;

create or replace procedure bbs(v_pid article.pid%type,v_level binary_integer) is
   cursor c is select * from article where pid= v_pid;
   v_preStr varchar2(1024):='';
begin
   for i in 1..v_level loop
      v_preStr := v_preStr ||'****';
   end loop;

   for v_article in c loop
       dbms_output.put_line(v_preStr||v_article.cont);
       if(v_article.isleaf = 0) then
           p(v_article.id,v_level+1);
       end if;
   end loop;
end;

--Oracle date默认格式:11-12月-1997 or 11-12月-97
--更改输入格式
alter session set nls_date_format='yyyy-mm-dd hh:mi:ss';

1.insert into...
1.savepoint a;
3.delete from stu;--删除所有记录,表结构还在,写日志，可以恢复，速度慢
4.rollback to a;

truncate table stu；--删除所有记录，表结构还在，不写日志，无法恢复，速度快
set timing on;

--union all和union的区别在于后者会去掉重复行
--minus，intersect

--创建数据库
--使用 Configuration and Migration Tools->Database Configuration Assistant 8步，默认20进程

--只读事务
set transaction read only;

--预定义角色是在数据库安装后，系统自动创建的一些常用的角色
--1．CONNECT,RESOURCE,DBA ---这些预定义角色主要是为了向后兼容。其主要是用于数据库管理。oracle建议用户自己设计数据库管理和安全的权限规划，而不要简单的使用这些预定角色。将来的版本中这些角色可能不会作为预定义角色。
--2．DELETE_CATALOG_ROLE,EXECUTE_CATALOG_ROLE,SELECT_CATALOG_ROLE ---这些角色主要用于访问数据字典视图和包。
--3. EXP_FULL_DATABASE,IMP_FULL_DATABASE ---这两个角色用于数据导入导出工具的使用。
select * from role_sys_privs  where role=upper('connect');
--对象权限就是指在表、视图、序列、过程、函数或包等对象上执行特殊动作的权利。有九种不同类型的权限可以授予给用户或角色
--系统权限需要授予者有进行系统级活动的能力,如连接数据库,更改用户会话、建立表或建立用户等等。你可以在数据字典视图SYSTEM_PRIVILEGE_MAP上获得完整的系统权限。对象权限和系统权限都通过GRANT语句授予用户或角色。需要注意的是在授予对象权限时语句应该是WITH GRANT OPTION子句，但在授予系统权象时语句是WITH ADMIN OPTION;
--查看死锁信息&解除死锁
select sess.sid,
       sess.serial#,
       lo.oracle_username,
       lo.os_user_name,
       ao.object_name,
       lo.locked_mode
  from v$locked_object lo, dba_objects ao, v$session sess
 where ao.object_id = lo.object_id
   and lo.session_id = sess.sid;

   SELECT a.sid, b.owner, object_name, object_type
  FROM v$lock a, all_objects b
 WHERE TYPE = 'TM'
   and a.id1 = b.object_id;

alter system kill session '3267,62017'

--查看死锁机器
select username, lockwait, status, machine, program
  from v$session
 where sid in (select session_id from v$locked_object)

 --查看死锁字段
 select sql_text
  from v$sql
 where hash_value in
       (select sql_hash_value
          from v$session
         where sid in (select session_id from v$locked_object));