Oracle10g 基本命令

 

第一课：客户端
        1. Sql Plus(客户端），命令行直接输入：sqlplus，然后按提示输入用户名，密码。
        2. 从开始程序运行:sqlplus，是图形版的sqlplus.
        3. http://localhost:5560/isqlplus
       
        Toad：管理， PlSql Developer:

第二课：更改用户
        1. sqlplus sys/bjsxt as sysdba
        2. alter user scott account unlock;(解锁)

第三课：table structure
       
        1. 描述某一张表：desc 表名
        2. select * from 表名
第四课：select 语句：

       1.计算数据可以用空表：比如：.select 2*3 from dual

       2.select ename,sal*12 annual_sal from emp;与select ename,sal*12 "annual sal" from emp;区别，加双引号保持原大小写。不加全变大写。
      
       3. select ename || "abcd" 如果连接字符串中含有单引号，用两个单引号代替一个单引号。

第五课：distinct
        select deptno from emp;
        select distinct deptno from emp;

        select distinct deptno from emp;
        select distinct deptno ,job from emp
        去掉deptno,job两者组合的重复。更多的项，就是这么多项的组合的不重复组合。
第六课：Where
        select * from emp where deptno =10;
        select * from emp where deptno <>10;不等于10       
        select * from emp where ename ='bike';
        select ename,sal from emp where sal between 800 and 1500 (>=800 and <=1500)
        空值处理:
        select ename,sal,comm from emp where comm is (not) null;
        select ename,sal,comm from emp where ename ( not)in ('smith','king','abc');
        select ename from emp where ename like '_A%';_代表一个字母,%代表0个或多个字母. 如果查询%
        可用转义字符.\%. 还可以用escape '$'比如:select ename from emp where ename like '%$a%' escape '$';

第七课: orderby
       
         select * from dept;
         select * from dept order by dept desc;(默认:asc)
         select ename,sal,deptno from emp order by deptno asc,ename desc;

第八课: sql function1:   
        select ename,sal*12 annual_sal from emp
        where ename not like '_A%' and sal>800
        order by sal desc;

        select lower(ename) from emp;

        select ename from emp
        where lower(ename) like '_a%';等同于
        select ename from emp where ename like '_a%' or ename like '_A%';

        select substr(ename,2,3) from emp;从第二字符截,一共截三个字符.
        select chr(65) from dual 结果为:A
        select ascii('a') from dual 结果为:65
        select round(23.652,1) from dual; 结果为: 23.7
        select round(23.652,-1) from dual; 20
 
        select to_char(sal,'$99_999_999') from emp;
        select to_char(sal,'L99_999_999') from emp;人民币符号,L:代表本地符号

        这个需要掌握牢:
        select birthdate from emp;
        显示为:
        BIRTHDATE
        ----------------
        17-12月-80
        ----------------

        改为:
        select to_char(birthdate,'YYYY-MM-DD HH:MI:SS') from emp;
       
        显示:
        
        BIRTHDATE
        -------------------
        1980-12-17 12:00:00
        -------------------
       
        select to_char(sysdate,'YYYY-MM-DD HH24:MI:SS') from dual; //也可以改为:HH12
        TO_CHAR(SYSDATE,'YY
        -------------------
        2007-02-25 14:46:14
       

        to_date函数:
        select ename,birthdate from emp where birthdate > to_date('1981-2-20 12:34:56','YYYY-MM-DD HH24:MI:SS');
        如果直接写 birthdate>'1981-2-20 12:34:56'会出现格式不匹配,因为表中的格式为: DD-MM月-YY.
 
       
        select sal from emp where sal>888.88 无错.但
        select sal from emp where sal>$1,250,00;
        会出现无效字符错误.
        改为:
        select sal from emp where sal>to_number('$1.250.00','$9,999,99');
       
        把空值改为0
        select ename,sal*12+nvl(comm,0) from emp;
        这样可以防止comm为空时,sal*12相加也为空的情况.

第九课: Group function 组函数
        max,min,avg ,count,sum函数
       
        select to_char(avg(sal),'99999999,99') from emp;
       
       
        select round(avg(sal),2) from emp;
        结果:2073.21
         
        select count(*) from emp where deptno=10;
        select count(ename) from emp where deptno=10; count某个字段,如果这个字段不为空就算一个.
        select count(distinct deptno) from emp;
        select sum(sal) from emp;

第十课: Group by语句
       
        需求:现在想求,求每个部门的平均薪水.
        select avg(sal) from emp group by deptno;
        select deptno avg(sal) from emp group by deptno;
       
        select deptno,job,max(sal) from emp group by deptno,job;
       
       求薪水值最高的人的名字.
       select ename,max(sal) from emp;出错,因为max只有一个值,但等于max值的人可能好几个,不能匹配.
       应如下求:
       select ename from emp where sal=(select max(sal) from emp);

       Group by语句应注意,

       出现在select中的字段,如果没出现在组函数中,必须出现在Group by语句中.
       
   
  第十一课: Having 对分组结果筛选
      
       Where是对单条纪录进行筛选,Having是对分组结果进行筛选.
     
       select avg(sal),deptno from emp
       group by deptno
       having avg(sal)>2000;
      
       查询工资大于1200雇员,按部门编号进行分组,分组后平均薪水大于1500,按工薪倒充排列.
       select * from emp
       where sal>1200
       group by deptno
       having avg(sal)>1500
       order by avg(sal) desc;
       
   第十二课:字查询
      
       谁挣的钱最多(谁:这个人的名字,  钱最多)
      
       select 语句中嵌套select 语句,可以在where,from后.
      
            
       问那些人工资,在平均工资之上.
      
       select ename,sal from emp where sal>(select avg(sal) from emp);

       查找每个部门挣钱最多的那个人的名字.
       select ename ,deptno from emp where sal in(select max(sal) from ename group by deptno) 查询会多值.

       应该如下:
      
       select  max(sal),deptno from emp group by deptno;当成一个表.语句如下:
       select ename, sal from emp join(select  max(sal) max_sal,deptno from emp group
       by deptno) t on(emp.sal=t.max_sal and emp.deptno=t.deptno);
      
       每个部门的平均薪水的等级.
       分析:首先求平均薪水(当成表),把平均薪水和另外一张表连接.
      
      
第十四课:self_table_connection
      
       把某个人的名字以及他的经理人的名字求出来(经理人及这个人在表中同处一行)
      
       分析:首先求出这个人的名字,取他的编号,然后从另一张表与其相对应编号,然后找到经理的名字.
      
       select e1.ename ,e2.ename from emp e1,emp e2 where e1.mgr= e2.empno.
      
       empno编号和MGR都是编号.

第十15课: SQL1999_table_connections   
        
      select ename,dname,grade from emp e,dept d, sqlgrade s
      where e.deptno = d.deptno and e.sql between s.losal and s.hisal and
      job<>'CLERK';
     
      有没有办法把过滤条件和连接条件分开来? 出于这样考虑,Sql1999标准推出来了.有许多人用的还是
      旧的语法,所以得看懂这种语句.
     
     
     
      select ename,dname from emp,dept;(旧标准).
      select ename,dname from emp cross join dept;(1999标准)
      
      select ename,dname from emp,dept where emp.deptno=dept.deptno (旧)
      select ename,dname from emp join dept on(emp.deptno = dept.deptno); 1999标准.没有Where语句.
      select ename,dname from emp join dept using(deptno);等同上句,但不推荐使用.
     
      select ename,grade from emp e join salgrade s on(e.sal between s.losal and s.hisal);
      join 连接语句, on过滤条件。连接，条件一眼分开。如果用Where语句较长时，连接语句和过滤语句混在一起。
     
      三张表连接：
      slect ename,dname, grade from
      emp e join dept d on(e.deptno=d.deptno)
      join salgrade s on(e.sal between s.losal and s.hisal)
      where ename not like '_A%';
      把每张表连接 条件不混在一起，然后数据过滤条件全部区分开来。读起来更清晰，更容易懂一点。
     
      select e1.ename,e2.ename from emp e1 join emp e2 on(e1.mgr = e2.emptno);

      左外连接：会把左边这张表多余数据显示出来。
      select e1.ename,e2,ename from emp e1 left join emp e2 on(e1.mgr =e2.empno);left 后可加outer
      右外连接：
    select ename,dname from emp e right outer join dept d on(e.deptno =d.deptno); outer可以取掉。
       
      即把左边多余数据，也把右边多余数据拿出来，全外连接。
      select ename,dname from emp e full join dept d on(e.deptno =d.deptno);

16-23 课：求部门平均薪水的等级

       A.求部门平均薪水的等级。

       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)
      
       B.求部门平均的薪水等级
       select deptno,avg(grade) from
       (select deptno,ename, grade from emp join salgrade s on(emp.sal between s.losal and
       s.hisal)) t
       group by deptno

       C.那些人是经理
       select ename from emp where empno in(select mgr from emp);
       select ename from emp where empno in(select distinct mgr from emp);
      
       D.不准用组函数，求薪水的最高值（面试题）
      
       select distinct sal from emp where sal not in(
       select distinct e1.sal from emp e1 join emp e2 on (e1.sal<e2.sal));
      
       E.平均薪水最高的部门编号
      
       select deptno,avg_sal from
       (select avg(sal)avg_sal,deptno from emp group by deptno)
       where avg_sal=
       (select max(avg_sal)from
       (select avg(sal) avg_sal,deptno from emp group by deptno)
       )
     
       F.平均薪水最高的部门名称
       select dname from dept where deptno=
      (
        select deptno from
        (select avg(sal)avg_sal,deptno from emp group by deptno)
        where avg_sal=
        (select max(avg_sal)from
        (select avg(sal) avg_sal,deptno from emp group by deptno)
        )
       )
     
      G.求平均薪水的等级最低的部门的部门名称
       
        组函数嵌套
        如：平均薪水最高的部门编号，可以E.更简单的方法如下：
        select deptno,avg_sal from
        (select avg(sal) avg_sal,deptno from emp group by deptno)
        where avg_sal =
        (select max(avg(sal)) from emp group by deptno)
       
        组函数最多嵌套两层
       
        分析：
        首先求
        1.平均薪水： select avg(sal) from group by deptno;

        2.平均薪水等级：  把平均薪水当做一张表，需要和另外一张表连接salgrade
        select  deptno,grade avg_sal 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)
       
        上面结果又可当成一张表。
       
        DEPTNO    GRADE    AVG_SAL
      --------  -------  ----------
        30           3   1566.66667
        20           4   2175
        10           4   2916.66667

        3.求上表平均等级最低值
       
        select min(grade) from
        (
          select deptno,grade,avg_sal 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.hisa)
         )

        4.把最低值对应的2结果的那张表的对应那张表的deptno, 然后把2对应的表和另外一张表做连接。
         
          select dname ,deptno,grade,avg_sal from
            (
         select deptno,grade,avg_sal 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)
             ) t1
            join dept on (t1.deptno = dept.deptno)
            where t1.grade =
            (
              select deptno,grade,avg_sal 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)
               )
            )
         结果如下：
        
        DNAME    DEPTNO     GRADE    AVG_SAL
      --------  -------  --------   --------
        SALES        30        3    1566.6667
    
        
       H: 视图（视图就是一张表，一个字查询）
       
       G中语句有重复，可以用视图来简化。
       conn sys/bjsxt as sysdba;
       grant create table,create view to scott;
       conn scott/tiger
       创建视图：
       create view v$_dept_avg-sal_info as
       select deptno,grade,avg_sal from
        ( select deptno,avg(sal) avg_sal from emp group by deptno)t
       join salgrade s on 9t.avg_sal between s.losal and s.hisal)
     
       然后
       select * from v$_dept_avg-sal_info
      
       结果如下：
       DEPTNO      GRADE    AVG_SAL
      --------  -------  ----------
        30           3   1566.66667
        20           4   2175
        10           4   2916.66667

       然后G中查询可以简化成：
       select  dname,t1.deptno,grade,avg_sal from
       v$_dept_avg-sal_info t1
       join dept on9t1.deptno =dept.deptno)
       where t1.grade=
       (
 select min(grade) from v$_dept_avg-sal_info t1
       )

--变量声明，使用%type属性
  declare
   v_empno number(4);
   v_empno2 emp.empno%type;
   v_empno3 v_empno2%type;
 begin
   dbms_output.put_line('test');
 end;

--table变量类型(数组)
declare
   type type_table_emp_empno is table of emp.empno%type index by binary_integer;
      v_empnos type_table_emp_empno;
begin
   v_empnos(0) := 7369;
    v_empnos(2) := 7839;
    v_empnos(-1) := 9999;
    dbms_output.put_line(v_empnos(-1));
end;

--record变量类型（近似java中的类）
declare
  type type_record_dept is record
      (
        deptno dept.deptno%type,
        dname dept.dname%type,
        loc dept.loc%type
      );
    v_temp type_record_dept;
begin
  v_temp.deptno := 50;
  v_temp.dname := 'aaa';
  v_temp.loc := 'bj';
  dbms_output.put_line(v_temp.deptno || ' ' || v_temp.dname);
end;

--使用%rowtype声明record变量
declare
  v_temp dept%rowtype;
begin
    v_temp.deptno := 50;
    v_temp.dname := 'aaa';
    v_temp.loc := 'bj';
   dbms_output.put_line(v_temp.deptno || ' ' || v_temp.dname);
end;

--SQL语句的运用
--select语句
declare
     v_name emp.ename%type;
     v_sal emp.sal%type;
begin
   select ename, sal into v_name, v_sal from emp where empno = 7369;
   dbms_output.put_line(v_name || ' ' || v_sal);
end;

declare
    v_emp emp%rowtype;
begin
  select * into v_emp from emp where empno = 7369;
  dbms_output.put_line(v_emp.ename);
end;

--insert语句

declare
    v_deptno dept.deptno%type := 50;
    v_dname dept.dname%type := 'aaa';
    v_loc dept.loc%type := 'bj';
begin
  insert into dept2 values(v_deptno, v_dname, v_loc);
 commit;
end;

declare
   v_deptno emp2.deptno%type := 10;
   v_count number;
begin
  --update emp2 set sal = sal/2 where deptno = v_deptno;
  --select deptno into v_deptno from emp2 where empno = 7369;
  select count(*) into v_count from emp2;
  dbms_output.put_line(sql%rowcount || '条记录被影响');
 commit;
end;

DDL语句
begin
     execute immediate 'create table t (nnn varchar2(20) default ''aaa'')';
end;

--if语句
取出7369的薪水，如果<1200，输出'low'，如果<2000输出'middle'，否则'high'

declare
    v_sal emp.sal%type;
begin
   select sal into v_sal from emp
          where empno = 7369;
   if (v_sal < 1200) then
         dbms_output.put_line('low');
   elsif (v_sal < 2000) then
         dbms_output.put_line('middle');
   else
         dbms_output.put_line('high');
   end if;
end;

--练习

 

--循环
declare
   i binary_integer := 1;
begin
   loop
      dbms_output.put_line(i);
           i := i + 1;
           exit when (i >= 11);
   end loop;
end;
---------
declare
   j binary_integer := 1;
begin
  while j < 11 loop
      dbms_output.put_line(j);
          j := j + 1;
  end loop;
end;

-----------
begin
    for k in 1..10 loop
       dbms_output.put_line(k);
    end loop;

    for k in reverse 1..10 loop
        dbms_output.put_line(k);
     end loop;
end;

--错误处理
declare
   v_temp number(4);
begin
   select empno into v_temp from emp where empno = 10;
exception
   when too_many_rows then
      dbms_output.put_line('太多纪录了');
   when others then
      dbms_output.put_line('error');
end;

----------

declare
   v_temp number(4);
begin
   select empno into v_temp from emp where empno = 2222;
exception
   when no_data_found then
      dbms_output.put_line('没有数据');
end;

---------
--创建事件日志表
create table errorlog
(
id number primary key,
errcode number,
errmsg varchar2(1024),
errdate date
)
--创建序列
create sequence seq_errorlog_id start with 1 increment by 1
--实验
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;

--游标
declare
   cursor c is
            select * from emp;
   v_temp c%rowtype;
begin
    open c;
    fetch c into v_temp;
    dbms_output.put_line(v_temp.ename);
    close c;
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;

--带参数的游标
declare
   cursor c (v_deptno emp.deptno%type, v_job emp.job%type)
   is
     select ename, sal from emp where deptno = v_deptno and job = v_job;
begin
   for v_temp in c(30,'CLERK') loop
      dbms_output.put_line(v_temp.ename);
   end loop;
end;

--可更新的游标
declare
  cursor c
  is
    select * from emp2 for update;
begin
   for v_temp in c loop
      if (v_temp.sal < 2000) then
         update emp2 set sal = sal * 2 where current of c;
      elsif (v_temp.sal = 5000) then
         delete from emp2 where current of c;
      end if;
    end loop;
    commit;
end;
----------------
--存储过程
create or replace procedure p
is
  cursor c
  is
    select * from emp2 for update;
begin
   for v_temp in c loop
      if (v_temp.deptno = 10) then
         update emp2 set sal = sal + 10 where current of c;
      elsif (v_temp.deptno = 20) then
         update emp2 set sal = sal + 20 where current of c;
      else
         update emp2 set sal = sal + 50 where current of c;
      end if;
    end loop;
    commit;
end;
--执行
exec p;
或
begin;
 p;
end;
--带参数的存储过程
create or replace procedure p
     (v_a in number, v_b number, v_ret out number, v_temp in out number)
is
begin
   if (v_a > v_b) then
      v_ret := v_a;
   else
      v_ret := v_b;
   end if;
   v_temp := v_temp + 1;
end;

--实验
declare
 v_a number := 3;
 v_b number := 4;
 v_ret number;
 v_temp number := 5;
begin
 p(v_a, v_b, v_ret, v_temp);
 dbms_output.put_line(v_ret);
 dbms_output.put_line(v_temp);
end;
-------------------
--函数
create or replace function sal_tax
  (v_sal number)
  return number
is
begin
   if (v_sal < 2000) then
      return 0.10;
   elsif (v_sal < 2750) then
      return 0.15;
   else
      return 0.20;
   end if;
end；

--触发器
create table emp2_log
(
uname varchar2(20),
action varchar(10),
atime date
)
-----------
create or replace trigger trig
  after insert or update or delete on emp2
begin
  if inserting then
     insert into emp2_log values (USER, 'insert', sysdate);
  elsif updating then
     insert into emp2_log values (USER, 'update', sysdate);
  elsif deleting then
     insert into emp2_log values (USER, 'delete', sysdate);
  end if;
end;

----------
update emp2 set sal = sal * 2 where deptno = 30;
--------
create or replace trigger trig
  after insert or update or delete on emp2 for each row
begin
  if inserting then
     insert into emp2_log values (USER, 'insert', sysdate);
  elsif updating then
     insert into emp2_log values (USER, 'update', sysdate);
  elsif deleting then
     insert into emp2_log values (USER, 'delete', sysdate);
  end if;
end;
-------------
--不提倡使用
create or replace trigger trig
 after update on dept for each row
begin
 update emp2 set deptno = :NEW.deptno where deptno = :OLD.deptno;
end;
----------------------
--树状结构的存储与展现
drop table article;

create table article
(
id number primary key,
cont varchar2(4000),
pid number,
isleaf number(1), --0代表非叶子节点，1代表叶子节点
alevel number(2)
)
-------------
insert into article values (1, '蚂蚁大战大象', 0, 0, 0);
insert into article values (2, '大象被打趴下了', 1, 0, 1);
insert into article values (3, '蚂蚁也不好过', 2, 1, 2);
insert into article values (4, '瞎说', 2, 0, 2);
insert into article values (5, '没有瞎说', 4, 1, 3);
insert into article values (6, '怎么可能', 1, 0, 1);
insert into article values (7, '怎么没可能', 6, 1, 2);
insert into article values (8, '可能性是很大的', 6, 1, 2);
insert into article values (9, '大象进医院了', 2, 0, 2);
insert into article values (10, '护士是蚂蚁', 9, 1, 3);
commit;
---------
蚂蚁大战大象
   大象被打趴下了
      蚂蚁也不好过
      瞎说
         没有瞎说
      大象进医院了
         护士是蚂蚁
   怎么可能
         怎么不可能
         可能性是很大的
--------------------------
create or replace procedure p (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;