语源科技BlogJava-Richard

Manager User

康文 — Thu, 12 Oct 2006 01:49:00 GMT

create user test1 identified by test1;
grant connect,create table to test1;
conn cyts_cc/cyts_cc@orcl2000;
create table(
id int)
tablespace user;
ERROR 位于第 1 行:
ORA-01950: 表空间'USERS'中无权限
conn cyts_cc/cyts_cc@orcl2000;
alter user test1 quota 1M on users;
create tab
(id int);
success
alter user test1 account lock;
conn test1/test1@orcl2000;
ERROR:
ORA-28000: the account is locked
1 Database Schema
a schema is a named collection of objects
b user is created and a corresponding schema is created
c user can be associated only with one schema
d username and schema are often userd interchangely.
2 Checklist for creating users
a idntfigy tablespaces in which the usr nedds to store objects
b decide on quotas for each tablespace
c assign a default tablespace and temporary tablespace.if you do not specify at the time of create user,system tablespace will be the defalut tablespace and temporary.it will affect the performance of the oralce.
d create user
e grant privileges and roles to user
desc dba_users;
select * from dba_users;
3 Creating a new user:
Database Authentiacation
set the initial password
create user aaron
identified by soccer
default tablespace data
temporary tablespace temp
guota 15m on data
password expire;

alter database default temporary tablespace temp;
4 Creating a new user operating System Authentication
os_authent_prefix initialllization parameter specifies the format of the username
defauts to ops$
    create user arron
    identified externally
    default tablespace users
    temporary tablespace temp
    quota 15m on data
    password expire;

    conn /
    show parameter os
    os_authent_prefix                    string                           OPS$
    create user ops$test3
      identified externally
      default tablespace us
      temporary tablespace
      quota 10m on users
    thee test2 is an user of os ,which the oracle is installed.
5 Changing user quota on tablespace
alter user test3 quota 4m on users;
you cann't grant quota on temp and undotbs.

alter quota 0 on uers -- means that no new table space can be allocated and cannot change the exist object in the tablespaces
6 drop user
you cannot drop user who has connected to oracle
drop user (cascade)
7 Obtaining User information
information about uers can be obtained by qerying the data dictionary
dba_users
名称
-----------------------------
USERNAME
USER_ID
PASSWORD
ACCOUNT_STATUS
LOCK_DATE
EXPIRY_DATE
DEFAULT_TABLESPACE
TEMPORARY_TABLESPACE
CREATED
PROFILE
INITIAL_RSRC_CONSUMER_GROUP
EXTERNAL_NAME
dba_ts_quotas
   名称
---------------
TABLESPACE_NAME
USERNAME
BYTES
MAX_BYTES
BLOCKS
MAX_BLOCKS

康文 2006-10-12 09:49 发表评论

Using SET Operators.

康文 — Wed, 11 Oct 2006 06:51:00 GMT

1 The Union Operator
The union operator returns results form both queries after eliminating duplications.\
select employee_id,job_id
from employees
uniion
select employ_id ,job_id
from job_history;
2 the all operator
The union all opertor reutrn result from both queries,including all duplications
3 interset
select ster_id,qty from sales where qty>20;
intersect
select ster_id,qty from sales where ster_id like '7%';
4 minus
select ster_id,qty from sales where qty>20
minus
select ster_id from sales where ster_id like '7%'

5 set operator guidelines
. teh expressions in the select list must match in number and data type;
. Parentheses can be used to alter the sequence of the execution
.The order by clause:
can appear only at the very end of the statement
will accept the column name,aliases from thee firest select statement ,or thee positional notation
.Duplicate row are atuomatically eliminated except in union all.
.Column names from the first query appear in the result
.The output is sorted in ascending order by default except in union all
6 matching the select statement
select department_id,to_number(null),location,hire_date
from employees
union
select department_id,location_id,to_date(null)
from departments;

select employee_id,job_id,salary
from employees
union
select employee_id,job_id,0
from job_history;
7 Controlling the order of the rows
select 'sing' as "my dream" ,3,a_dummy
from dual
union
select 'like''d like to teach',1
from dual
union
select 'the world to',2
from dual
order by 2;

康文 2006-10-11 14:51 发表评论

开发子过程

康文 — Wed, 11 Oct 2006 06:51:00 GMT

1 开发过程
1) 建立过程：不带参数
create or replace procedure out_time
is
begin
    dbms_output.put_line(systimestamp);
end;
a 使用execute 命令调用过程
   set serveroutput on
   exec out_time;
b 使用call 命令调用过程
   set serveroutput on
   call out_time();
2) 建立过程：带有in参数默认为输入参数，另外也可以使用in 关键子显示的定义
   create or replace procedure add_employee
   (eno number,name varchar2,sal number,
    job varchar default 'clerk',dno number)
   is
   e_integrity exception;
   pragma exception_init(e_intgegrity,-2291);
   begin
    insert into emp(empno,ename,sal,job.deptno)
      values(eno.name,sal,job,dno);
    exception
      when dup_val_on_index then
        raise_application_error(-20000,'雇员号不能重复');
      when e_integrity then
        raise_application_error(-20001,'部门号不存在');

调用
   exec add_employee(111,'clark',200,'manager',10);
   3 建立过程，带有out 参数
    create or replcace procedure query_employee
    (eno number,name out varchar2,salary out number)
    is
    begin
      select ename,sal,into name,salary from emp where empno=eno;
    exception
      when no_data_found then
        raise_application_error(-20000,'G该雇员不存在');
    end;

    调用
    var name varchar2(10)
    var salary number
    exec query_employee(7788,:name,:salary);
    print name,salary;
    4 建立过程，带有in out 参数
    create or replace procedure compute
    (num1,in out number,num2 in out number)
    is
       v1 number;
       v2 number;
    begin
      v1:=num1/num2;
      v2:=mod(num1,num2);
      num1:=v1;
      num2:=v2;
    end;

    调用
    var n1 number
    var n2 number
    exec :n1:=100;
    exec :n2:=30
    exec compute(:n1,:n2)
    print n1 n2
    5) 为参数传递变量和数据位置传递，名称传递，组合传递
    create or replace procedure add_dept
    (dno number,dname varchar2 default null,loc varchar default null)
    is
    begin
      insert into dept values(dno.dname,loc);
    end;
    -- 位置传递
     exec add_dept(50,'sales','new york');
     exec add_dept(60);
     exec add_dept(70,'admin');
    -- 名称传递
     exec add_dept(50,loc=>'new york');
     exec add_dept(60,dname=>'sales',loc=>'new york');
   6) 显示当前用户的所有程序及其源代码
     select text from user_source where name='add_dept';
   7) 删除过程
     drop procedure add_dept;
2 开发函数
可以在sql语句和其他子过程中执行。
1 建立函数，不带任何参数
create or replace function get_user
return varchar2
is
    v_user varchar2(100);
begin
    select username into v_user from user_users;
    return v_user;
    end;
--使用变量接收函数返回值
   var v2 varchar2(100)
   exec :v1:=get_user
   print v1;
-- 在sql 语句中直接调用函数
   select get_user from dual;
-- 使用dbms_output 调用函数
   set serveroutput on
   exec dbms_output.put_line('get_user');
2) 建立函数，带有in 参数
   create or replace function get_sal(name in varchar2)
   reutnr number
   as
   v_sal emp.sal%type;
   begin
     select sal into v_sal from emp where upper(ename)=upper(name);
     return v_sal;
   exception
     when no_data_found then
       raise_application_error(-20000,'employee does not exist');
   end;
3) 建立函数，带有out 参数
   create or replace function get_info
   (name varchar2,title out varchar2)
   return varchar2
   as
     deptname dept.dname%type;
   begin
     select a,job,b,dname into title,deptname from emp a,dept b
     where a.deptno=b.deptno
     and upper(a.ename)=uppder(name);
     return deptname;
   end;
   var job varchar2(20)
   var dname varchar2(20)
   exec :dname:=get_info('scott',job);
   print dname job

4) 带有 in out 参数
create or replace function result
(num1,number,num2 in out nu8mber)
return number
as
    v_result number(6);
    v_remainder number;
begin
    v_result:=num1/num2;
    v_remainder:=mod(num1,num2);
    num2:=v_remainder;
    retrun v_result;
exception
    when zero_divide then
       raise_application_error(-20000,'zero divied');
end;
5) 函数调用的限制
-- 在sql 语句中只能调用存储函数
-- 在sql 语句中只能调用带有输入参数in ，而不能有输出参数out 和in out 参数的函数
-- 在sql 语句中调用的函数的参数必须是标准的sql 数据类型，不能是pl/sql 所特有的数据类型
-- 在sql 语句中调用的函数不能包含insert，update 和delete
6) 查看源代码
set pagesize 40
select text form user_source where name='result';
7) 删除函数
drop function result;
3 管理子程序
1) 列出当前用户的子程序
   select object_name,created,status form user_objects
   where object_type in ('procedure','function');
2)列出子程序源代码
   select text from user_sorce where name='raise_salary'
3)类出子程序编译错误
    -- show errors
    --使用数据字典user_errors 确定错误原因和位置
     select line||'/'||position as "line/col",text error
     from user_errors where name='raise_salary';
   4) 列出对象的依赖关系
    -- 使用 user_dependenciess 确定直接依赖关系
    select name,type from user_dependencies
    where referenced_name='emp'
    -- 使用 deptree 和 ideptree 确定依赖和见解依赖关系
    select nested_level,name,type from deptree;
   5) 重新编译子程序
     当被应用对象的结构被修改以后，就会将相关依赖对象转变为无效invalid ，需要重新编译
     1
     alter table emp add remark varchar2(100);
     2
     select object_name,object_type from user_objects
     where status='invalid'
     3
     alter procedure add_employee compile;
     alter view dept10 compile;
     alter function get_info compile;

康文 2006-10-11 14:51 发表评论

处理例外

康文 — Wed, 11 Oct 2006 06:46:00 GMT

1例外简介
1）例外分类
预定义分类，非预定义分类，自定义例外。
2 处理预定义例外
1) 常用预定义例外
   a access_into_null;
     create type emp_type as object
     (name varchar2(2),sal number(6,2));

     declare
       emp emp_type;
     begin
       emp.name:='scott';
     exception
       when access_into_null then
          dbms_output.put_line('首先初始化对象emp');
    b case_not_found
     undef no
     declare
       v_val emp.sal%type;
     begin
       select sal into v_sal from emp where empno=&no;
       case
         when v_sal<1000 then
           update emp set sal=sal+100 where empno=&no;
         when v_sal<2000 then
           update emp set sal=sal+150 where empno=&no;
         when v_sal<3000 then
          update emp set sal=sal+200 where empno=&no;
       end case;
       exception
         when case_not_found then
           dbms_output.put_line();
      end;
    c collection is null
    在给集合元素（嵌套表或array类型）赋值前，必须首先初始化集合元素
    declare type ename_table_type is table of emp.eanme%type;
    ename_table ename_table_type;
    begin
      select e_name into ename_talbe(2) from emp where empno=$no;
    exception
      when collection_is_null then
        dbms_output.put_lilne('必须使用构造方法初始化集合元素');
    end;
    d currsor_already_open
    reopen curosr 如果用户已经使用了open 命令打开了显示游标，或执行for循环(隐式的打开游标)
       delcare
         cursor emp_surosr is select ename,sal,from emp;
       begin
         open emp_curosr;
         for emp_record in emp_cursor loop
              dbms_output.put_line(emp_record.eanme);
         end loop;
       exception
          when cursor_already_open then
            dbms_output.put_line("游标已经打开");
       end;
     e dup_val_on_index
     begin
     exception
        when dup_val_on_index then
        dbms_output.put_line("列上不能出现重复值");
     end;
     d invalid_curosr
     delcare
       curosr emp_cursor is select ename,sla from emp;
       emp_record emp_crusor%rowtype;
     begin
       fetch emp_cursor into emp_record;
       close emp_crusro;
     exception
       dbms_output.put_line("游标没有打开");
     end;
     f invalid_number can not convert char to nmuber successfully
       begin
         update mep set sal=sal+1oo;
       exception
         when invalid_number then
     g no_data_found when select into is executed ,no row is returned
       declare
         v_sal emp.sal%type;
       begin
          select sal into v_cal form emp where lower(ename)=lower('&name');
       exception
         when no_data_found then
             dbms_output.put_line('没有返回结果');
       end;
      h too_many_row ora -01422 there are too many are return when "select into" is executed
      i zero_divide ora-01476
      g subscript_beyond_count ora-065533
      declare
        type emp_array_type is varray(20) of varchar2(10);
        emp_array emp_array_type;
      begin
         emp_array:=emp_array_type('scott','mary');
         dbms_output.put_line('emp_array(3)');
      exception
         when subscript_beyone_count then
          dbms_out.put_line('超出下标范围');
      end;
      k subscript_outside_limit
       emp_array(-1);
      l value_error the length of variable cannot contain the actual value;
      declare
      begin
      end;
3 处理非预定义例外
delcare
    e_integrity exception;
    pragma exception_init(e_integrity,-2291);
begin
    update emp set deptno=dno where empno=&no;
exception
    when a_integrity then
end;
4 处理自定义例外
与oracle 错误没有任何联系，为业务逻辑所定义的例外
delcare
    e_no_employee exception;
begin
    update emp set deptno=&dno where empno=&eno;
if sql%notfound then
    raise e_no_employee;
end if;
exception
    when e_no_emplyee then
     dbms_output.put_line('该雇员不存在');
5 使用错误例外函数
使用例外函数可以取得错误号以及相关的错误消息，sqlcode 用于取得oracle 的错误号，而sqlerrm
则用于取得与之相关的错误信息。
1 sqlcode 和 sqlerrm
为了在pl/sql 应用程序中处理其他为预料的到的oracle 错误，用户可以在例外处理部分的
when others 自句后，引用两个函数
declare
    v_ename emp.ename%type;
begin
    select ename into v_ename form emp where sal='&v_sal';
exception
    when no_data_found then
    when others then
       dbms_output.put_line(sqlcode);
       dbms_output.put_line(sqlerrm);
end;
2 raise_aaplicaition_error
   只能在子程序中使用（过程，函数，包，触发器）
   raise_application_error(error_number,message,[true|false]);
   error_number 错误号，在－20000到－20999 之间
   message 指定错误消息，不能超过2048
   if v_comm is null then
       raise_application_error(-20001,'该雇员无补助');
   end if;

康文 2006-10-11 14:46 发表评论

开发包

康文 — Wed, 11 Oct 2006 06:46:00 GMT

1建立包
1) 建立包规范：用于定义包的公共组建，包括常量，变量，游标，过程和函数等
create or replace package emp_package is
g_deptno number(3):=30;
procedure add_employee(eno number,name varchar2,salary number dno number default g_deptno);
procedure fire_empoyee(eno number);
function get_sal(eno number) return number;
end emp_package;
2) 建立包体
   用于实现包规范所定义的过程和函数。在包体中也可以单独定义私有组件，包括变量，常量，过程和函数等。但在包体中所定义的组件只能在包内使用，而不能由其他子程序引用。
   create or replace package body emp_package is
    function validate_deptno(v_deptno number)
      return boolean;
    is
      v_temp int;
    begin
      select 1 into v_temp from dept where deptno=v_deptno;
      return true;
    exception
      when no_data_found then
       return false;
    end;
    procedure add_employee(eno number,name varchar2,salary number,dno number default g_deptno)
    is
    begin
      if validate_deptno(dno) then
        insert into emp(empno,ename,sal,deptno)
         values(eno,name,salary,dno);
      esle
        raise_application_error(-20011,'部门不存在');
      end if;
    exception
      when dup_val_on_index then
        raise_application_error(-20011,'该雇员已存在')
    end;
    procedure fire_employee(eno number) is
    begin
      select from emp where empno=eno;
      if sql%notfound then
         raise application_error(-20012,'');
      end if;
    end;
   function get_sal(eno number) return number
   is
     v_sal emp.sal%type;
   begin
     select sal into v_sal from emp where empno=eno;
     return v_sal;
   exception
     when no_data_found then
       raise_application_error(-200012,'');
   end;
end emp_package;
3) 调用包组建
    －－在同一个包内调用组建不需要加包名前缀，直接调用
create or replace paclage body emp_package is
    procedure add_employee(eno number,name varchar2,salary number,dno number default g_deptno)
    is
    begin
      validate_deptno(dno) then
    exception
    end;
   -- 调用包公用变量
   exec emp_package.g_deptno:=20
   -- 调用公用过程
   exec emp_package.add_employee(111,'mary,2000');
   -- 调用远程数据库包的公用组件
   exec emp_paclage.add_employee@orasrv(1116,'scott',1200);
   4) 查看包源代码
   select text from user_source where name='emp_package' and type='package';
   5) 删除包
   drop packagee emp_package;
2 使用包重载
指多个具有相同名字的子程序，在调用的时候使用不同的参数传递。
1) 建立包规范
   同名过程和函数必须具有不同的输入参数，但同名函数返回值的类型数据必须相同
    create or replace package overload is
    function get_sal(eno number) return number;
    function get_sal(name varchar2) return number;
    procedure fire_employee(eno number);
    procedure fire_employee(name varchar2);
   2) 建立包体
    。。。
3) 使用包构造过程
初始化全局变量
1 建立包规范
   create or replace packiage emp_package
   is
   minsal number(6,2);
   maxsal number(6,2);
   procedure upd_sal(eno number,salary number);
   procedure upd_sal(name varhcar2,salary number);
   end;-- 定义了两全局变量和三个公用过程
   2 建立包体
    create or replace package body emp_package is
      procedure add_employee(cno number,name varchar2,salary number,dno number)
      is
      begin
        if salary between minsal and maxsal then
          insert into emp(empno,ename,sal,deptno)
         ........
    -- 构造过程，位于子程序尾部，已begin 开始已end 结束
     begin
       select min(sal),max(sal) into minsal,maxsal from emp;
     end;
      end;
3 调用包公用组建
   在同一次会话中第一次调用包的公用组建时，会自动执行其它构造函数，而将来调用其他组建时则不会再调用其构造过程。
4 使用纯度级别
1 家里包规范
create or replcace package purity is
minsal number(6,2);
maxsal number(6,2);
function max_sal return number;
function min_sal return number;
pragma restrict_references(max_sal,wnps);--wnps 不能修改包的变量（不能给包的变量赋值）                                            --wnds 不能执行dml
pragma restrict_references(min_sal,wnps);--rnps 用于限制函数不能读取包变量
end;

康文 2006-10-11 14:46 发表评论

including Constraints

康文 — Wed, 11 Oct 2006 06:45:00 GMT

1 What are Constrains
1) Constrains enforce on the table level
2) Constrains the deletion of a table if there are dependencies
2 Constrain Guidelines
1) Name a constraint or the oracle generate a name by the sys_cn format
2) Create a constraint either
     --At the same time as the table is created.or
     --After the table has been created
3)Define a constraint at the column or table level
4)view constraint in the data dictionary
3 Crete a constraint
create table test2
(id int not null,-- column level
   lname varchar(20),
   fname varchar(20),
   constraint uk_test2_1 unique(lname,fname))--table level
4 The not null Constraint
create table employees(
   employee_id number(6),
   last_name   varchar2(25) not null --system named
   hire_date   DATE
               constraint emp_hire_date not null --User named
5Foreign key
create table test3
(rid int,
   name varchar(30),
   constraint fk_test3_1 foreign key(rid) reference test2(id));
froeign key constraint keywords
    foreign key :Define the column in thee child table at the table constrain level.
    references :Identifies the table and column in the parent table.
    on delete cascade: Delete the dependent rows in the child table when a row in the     parent table is deleted
    on delete set null:Convert the dependent foreign key values to null when a row in the
    parent table is deleted.

    --parent table referenced table
    --child table refernce other table
6 The check Constraint
Define a condition that each row must be satisfy
alter table test3
add constrain ch_test3 check(name like 's%')
7 Dropping a Constraint
1) Remove the manager constraint form the employee table
   alter table test3
   drop constriant test3_manager_fk
2) Remove the primary key constraint on the departments table and drop the associated
   foreign key constraint on the employees.department_id column
   alter table departments
   drop primary key cascade
8 Disabling and enable Constraints
1)Execute the disable clause of the alter table statment to deactive an integrity constraint
2)Apply the cascade option to disable dependent integrity constrints
alter table employees
disable constraint emp_emp_id_pl cascade
3) enabling Constraints
.Active an integrity constraint currently disabled in the table definition by using the enable clause.
   alter table employees
   enable constraint emp_emp_id_pk;
a unique or a primary index is automatically created if you enable a unique key or a primary key constraint
8 View Constraints
select constraint_name,constriant_type,serch_condition
from user_constraints
where table_name='employees'
9 view the columns associated with constraints
select constraint_name,column_name
from user_cons_columns
where table_name='employees'

康文 2006-10-11 14:45 发表评论

create view

康文 — Wed, 11 Oct 2006 06:45:00 GMT

1Why Use Views
to restrict data access
to make complex query easy
to provide data independence
to provide defferent view of the same data
2 Creating a View
1)create [or replace] [force|noforce] view view
as subquery
force : create view wether the referenced object existed or not

desc view_name;
2)create a view by using column aliases in the subquery
create view salv50
as select employee_idIO_NUMBER,last_name NAME,slaary*12 ANN_SALARY
from employees
where department_id=50;
3 Modigy a View
1) Modigy the emplvu80 view by using create or replace view clause.Add an alias for each column name;
   create or replace view empvu80
   (id_number,name,sal,department_id)
   as select employee_id,first_name||" "||last_name,salary.department_id
   from employees
   where department_id=80;
   column aliases in the create view clause are listed in the same order as the columns in the subquery
   note : alter view_name is not a valid command.
4 Create a Complex View
Create a complex view that contains group functions to display values from two tables
create view dept_sum_vu
   (name,minsal,maxsal,avgsal)
as
   select d.department_name,min(e.salary),max(e.salary),avg(e.salary)
   from employees e,departments d
   where e.department_id=d.department_id
   group by d.department_name;
5 Rules for performs DML operaton on a view
1) You can perform DML operation on simple views
2) You can not romove a row if the view contains the following:
    --group functions
    --a group by clause
    --the distinct keyword
    -- rownum keyword
    -- column defined by expressions
6 Using the with check option Clause
1) you can ensure that dml operatons performed on the view stay within the domain of the view by using the with check option clause.
create view test1
as
select * from emp where qty>10;
with check option;
update testview1 set qty=10
where ster_id=6830;
--when you doing the following update operation
update testview1 set qty=5 where id=10;
-- an error will report
--you violate the where clause
2)Any attempt to change the department number for any row in the view fails because it violates the with check option constraint
   create or replace view empvu20
   as
   select * where department_id=20
   with check option constriant empvu20_ck;
7 Denying DML Operations
1 You can ensure that no dml operations occur by adding the with read only option to your view definition.
2)Any attempt to a DML on any row in the view resuls in an oralce server error.
8 remove veiw
drop view_name
9 inline view
1) an inline view is a subquery with an alias that you can use within a sql statement.
2) a named subquery in the from clause of the main query is an exqmple of an inline view
3) an inline view is not a schema object.
10 Top-N Analysis
1)Top_N querise ask for the n largest or smallest values of a column.
2)Both largest values and smallest values sets considered Top-N queries
select * from (select ster_id,qty from sales);
example
To display the top three earner names and salaries from the employees
select rownum as rank,last_name,salary
from (select last_anme,slary from employee
        order by slary desc)
where rownum<=3;

康文 2006-10-11 14:45 发表评论

使用触发器

康文 — Wed, 11 Oct 2006 06:44:00 GMT

1 触发器简介
1) 触发事件
2) 触发条件
3) 触发操作
     . 触发器代码的大小不能超过32k，如果使用大量代码建立触发器，应该先建立存储过程，然后再触发器中使用call语句调用存储过程。
     . 触发器中正能含有select ，insert，update 和delete 语句，而不能含有ddl 语句，和事物控制语句。
2 建立dml 触发器
1) 触发时机
before，after 表示在执行dml操作之后触发器
2)触发事件
insert ，update 和delete 操作。也可以使用书法事件
3) dml 触发器是针对特定表进行的因此必须制定dml 操作所对应的表
4) 触发器类型用于指定当触发器事件之后，需要执行几次触发器操作。如果指定语句触发器类型
那么会执行一次触发器代码：如果指定行触发器类型，则会在每个被作用行上执行一次触发器代码。
5) 触发条件
用于指定执行行触发器代码的条件，只有为ture时，才会执行行触发器代码。
6) 如果使用pl/sql 存储过程，java 存储过程，或外部处处过程需要在触发器操作部分直接使用call
7) dml 触发器触发顺序
   (1)dml 触发器在单行数据上的触发顺序。
    对于单行数据而言，无论是语句此触发器，还是行触发器，触发器代码实际只执行一次，并且执行
顺序为before 语句触发器，before 行触发器，dml 操作，after 行触发器，after 语句触发器
   (2) dml 触发器在多行数据上的触发顺序
    before 语句触发器
    before 行触发器
    after 行触发器
    before行触发器
    after 行触发器
    after语句触发器
   语句触发器只被执行一次，而行触发器在每个行上都执行一次。
2) 语句触发器
当审计dml 操作，或确保dml操作安全执行时，可以使用语句触发器
1 建立before 语句触发器
   create or replace trigger tr_sec_emp
   before insert or update or delete on emp
   begin
     if to_char(sysdate,'DY','nls_dtate_language=AMERICAN') in ('sat','sun') then
     railse_application_error(-200001,'不能在休息日改变雇员信息');
     end if;
   end;
   2 使用条件谓词
   inserting ,updating ,deleting
   create or replace trigger tr_sec_emp
   before insert or update or delete on emp
   begin
     if to_char(sysdate,'DY','nls_date_language=american')
      in('sat','sun') then
     case
       when inserting then
         raise_application('-20001','inserting');
       when updating then
         raise_application('-20002','updating');
       when deleting then
         raise_application('-20003','deleting');
     end case;
    end if;
   end;
   3 建立after 语句触发器
    为了dml 操作，或者dml 操作后执行汇总运算
   create table aduit_table(
     name varchar2(20),ins int,upd int,del int,
     starttime date,endtime date
   );
   create or replace trigger tr_aduit_emp
   after insert or update or delete emp
   declare
     v_temp int;
   begin
     select count(*) into v_temp from aduit_table
       where name='emp';
     if v_temp=0 then
       insert into audit_table values
       ('emp',0,0,0,sysdate,null);
     end if;
     case
       when inserting then
         update aduit_table set ins=ins+1,endtime=sysdate where name='emp';
       when updating then
         update audit_table set upd=upd+1,endtime=sysdate where name='emp';
       when deleting then
         update aduit_table set del=del+1,endtime=sysdate where name='emp';
   end;
3) 行触发器
   审计数据变化可以使用行触发器
   1 建立不before 行触发器
    为了取保数据符合商业逻辑或企业规则，对输入的数据进行复杂的约束，可以使用before行触发器
     create or replace trigger tr_emp_sal
     before update of sal on emp
     for each row
     begin
       if :new.sal<:old.sla then
         raisse_application_error(-200010,'工资只涨不降');
       end if；
     end;
     2) 建立after 行触发器
     为了审计dml 操作，可以使用语句触发器或oracle 系统提供的审计功能，而为了审计数据变化
，则应该使用after 行触发器
     create table audit_emp_change(
       name varchar2(10),odl number(6,2),
       newsal number(6,2),time date);
    create or replace trigger tr_sal_change
    after update of sal on emp
    for each row
    declare
     v_temp int;
    begin
     select count(*) into v_temp from audit_emp_change where name=:old.ename;
    if v_temp =0 then
      insert into audit_emp_change
        values(:old,ename,:old.sal,:new,sal,sysdate);
    else
      update audit_emp_change
        set oldsal=:old.sal,newsal=:new.sal,time=sysdate where name=:old.ename;
    end if;

    end;
     )
    3) 限制行触发器
    当使用行触发器，默认情况下会咱每个被作用行上七星一次触发器代码，为了时得再特定条件下执行行触发器代码，需要使用when 子句
    create or replace trigger tr_sal_change
    after update of sal on emp
    for each row
    when(old.job='salesman')
    declare
       v_temp int..
2 dml 触发器使用注意事项
触发器代码不能从触发器所对应的基表中读取数据
3 dml 触发器
为了保证数据库满足特定的商业规则或企业逻辑，可以使用约束，触发器和子程序。约束性能最好，实现最简单，所以为售选，如果触发器不盟实现，可以选择触发器。
dml 触发器可以用于实现数据安全保护，数据审计，数据完整性，参照完整性，数据复制等功能。
1) 控制数据安全
create or replace trigger tr_emp_time
before insert or update or delete on emp
begin
    if to_char(sysdate,'hh24') not between '9' and '17' then
      raise_application_error(-20101,'not work time');
     end if;
end;
2) 实现数据审计
使用数据审计只能审计sql 操作，而不会记载数据变化
audit insert,update,delete on emp by access
3)实现数据完整性
首选约束 alter table emp add constraint ck_sal check (sal>=800),但是在有些情况下只能使用触发器来实现数据完整性
   create or replace trigger tr_check sal
   before update of sal on emp
   for each row
   when (new.sla1.2* old.sal)
   begin
      raise_application_error(,,,,,,)
   end;
3) 使用引用完整性
采用 on delete cascade 可以进行集联删除，但是却不能进行集联更新。采用触发器实现集联更新
   create or replace trigger tr_update
   after update of sal on emp
   for each row
   begin
     update emp set depno=:new.deptno where dentno=:old.deptno;
   end;
4 建立instead of 触发器
对于简单视图可以直接进行insert update 和delete 等操作，但是对于复杂视图不允许进行insert，update 和delete 操作。
满足一下条件的为复杂视图
    具有操作集合符 union，union all ，intersect，minus
    具有分组函数 min，max，avg，sum，count
    具有group by connect 编译或start with
    具有distinct
    具有连接
为了在复杂视图上执行dml 操作，必须要基于instead-of 触发器，建立instead－of 触发器后，就可以基于复杂视图执行insert，update和delete 语句。
   instead of 选项只使用于视图
   基于视图建立触发器时，不能定义before 和 after
   在建立视图时不能指定 with check option
   当建立instead of 触发器时，必须指定for each row 选项
1) 建立复杂视图dept_emp
   create or replace view dept_emp as
   select a.deptno,a.dname,b,empno,b,ename
   from dept a,emp b
   where a,deptno=b.deptno;
2) 建立 instead－of 触发器
   create of replacee trigger tr_instead_of_dept_emp
   instead of insert on dept_emp
   for each row
   declare
     v_temp int;
   beegin
      select count(*) into v_temp from dept where deptno=:new.deptno;
      if v_temp=0 then
        insert into dept(deptno,dname) values(:new.deptno,:new.dname);
      end if;
      select count(*)into v_temp from emp where empno=:new.empno;
      if v_temp=0 then
         insert into emp(empno,ename,deptno)
           values(:new.deptno,:new.ename,:new.deptno);
         end if;
   end;

   可以对视图执行insert 操作了
    insert into dept_emp values(50,'admin','1223','mary')
5 管理触发器
1) 显示触发器信息
    select trigger_name,status from user_triggers
    where table_name='emp';
   2)禁止触发器
    alter trigger tr_check_sal disable;
   3) 激活触发器
    alter trigger tr_check_sal enable;
   4) 禁止或激活表上的所有触发器
    alter table emp disable all triggers;
    alter table emo eanble all triggers;
   5)重新编译触发器
    alter trigger tr_check_sal compile;
   6) 删除触发器
    drop trigger tr_check_sal;

康文 2006-10-11 14:44 发表评论

使用复合变量

康文 — Wed, 11 Oct 2006 06:44:00 GMT

1 pl/sql 集合处理单列多行数据库，使用的类型为标量类型
1）索引表
type ename_table_type is table of emp.ename%type
    index by binary_integer;
ename_table ename_table_type;
begin
    select ename into ename_table(-1) from emp
      where empno=&no;
    dbms_output.put_line('雇员名：'||ename_table(-1));
end;

   set serveroutput no
   declare
     type area_table_type is table of number
        index by varchar2(10);
     rea_table area_table_type;
    begin
        area_table('beijing'):=1;
        area_table('shanghai'):=2;
        area_table('guangzhou'):=3;
        dbms_output.put_line(area_table.first);
        dbms_output.put_line(area_table.last);
    end;
     2) 嵌套表
      索引表类型不能作为累得数据类型使用，但是嵌套表可以作为表类的数据类型使用。
当使用嵌套表元素时，必须先用其构造方法初始化其嵌套表：
       a 在pl/sql 块中使用嵌套表
        declare
          type ename_table_type is table of emp.ename%type;
          ename_table ename_table_type;
        begin
           ename_table:=eanme_table_type('2','2','3');
           select ename into ename table(2) from emp where empno=&no;
           dbms_ouput.put_line(ename_table(2));
        end;
      b 在表中使用嵌套表
        create type phone_type is table of varchar2(20);
        create table employee(
          id number (4),name varchar2(10),sal number(6,2),
          phone phone_type
        )nested table phone store as phone_table;
       -- 为嵌套表插入数据
        insert into employee values(2,'scott',200,phone_type('2222','333333'));
       －－检索嵌套表累得数据
        set serveroutput on
        declare
          phone_table phone_type;
        begin
          select phone into phone_table
          from employee where id=1;
          for i in 1..phone_table.count loop
            dbms_output.put_line(phone_table(i));
          end loop;
        end;
       -- 更新嵌套表列的数据
         delcare
            phone_table phone_type:=('44444','555555');
         begin
            update employee set phone=phone_table
            where id=1;
         end;
    3) 变长数组
      在使用varray 时必须指定最大个数，和数据类型,在使用其元素时必须进行初始化
      type ename_table_type is varray(20) of emp.ename%type;
      ename_table ename_table_type:=ename_table_type('1','2');

      -- 在快中使用varray
      declare
         type ename_table_type is varray(20) of emp.ename％type；
         ename_table ename_table_type:=ename_table_type('mary');
         begin
            select ename into ename_table(1) form emp
               where empno=&no;
          end;
      --在表列中使用varray
       create type phone type is varray(20) of varchar2(20);
       create table employee(
         id number(4),name varchar2(10),
         sal number(6,2),phone phone_type);

     3)记录表
      记录表结合了记录和集合的优点
        declare
          type emp_table_type is table of emp%rowtype
          index by binary_integer;
        emp_table emp_table_type;
        begin
          select * from into emp_table(1) from emp
          where empno=&no;
          dbms_output.put_line(emp_table(1).ename);
        end;
      4)多维集合
       1 多级varray
       declare
        --define 一维集合
          type al_array_type is varray(10) of int;
        --定义二维集合
          type nal_varray_type is varray(10) of a1_varray_type;
        --初始化二维集合
          nvl nal_varray_type:=nal_varray_type(
             a1_varray_type(1,2),
            a1_varray_type(2,3)
          )
         beign
           for i in 1..nal_varray_type.count loop
              for j in 1..a1_array_type.count loop
                dbms_out.putline(nvl(i)(j));
              end loop;
           end loop;
        end;
       2 使用多级嵌套表
        table a1_table_type is table of int;
        table nvl_table_type is table of a1_table_type;
        nvl nvl_table_type:=nvl_table_type(
          a1_table_type(1,2),
          a1_table_type(2,3)
        );
2 集合方法
1) exist
   if ename_table.exists(1) then
    ename_table(1):='scott';
   2) count 返回当前集合变量中的元素总个数
    ename_table.count
   3) limit 返回集合元素的最大个数只有varray 有
   4)first and last
       ename_table.first
       ename_table.last
   5) prior 和next
    ename_table.prior(5); －－返回元素5的前一个
    ename_table.next(5); -- 后一个
   6) extend
    使用于varray 和嵌套表。
    extend add a null value
    extend (n) add n null value
    extend (n,i)add n i value
    declare
      type ename_table_type is varray(20) of varchar2(20);
      ename_table ename_table_type;
    begin
      ename_table:=ename_table_type('mary');
      ename_table.extend(5,1);
      dbms_output.put_line(ename_table.count);
    end;
   7) trim
   trim remove one element from the tail of the collection.
   trim(n) remove n element from the tail of the colleciton.
   8)delete
    delete: delete all the elements
    delete(n) :delete the nth elements
    delete(m,n): delete the elements from m to n
3 集合赋值
1)将一个集合的数据赋值给另一个集合.clear the destination collectins and set the original collection
   delcare
    type name_varray_type is varray(4) of varchar2(10);
    name_array1 name_varray_type;
    name_array2 name_varray_type;
   begin
     name_array1:=name_varray_type('scott','smith');
     name_array2:=name_array_type('a','b','c');
     name_array1:=name_array2;
   end;


type name_array1_type is varray(4) of varchar2(10);
type name_array2_type is varray(4) of varchar2(10);
name_array1 name_array1_type;
name_array2 name_array2_type;
具有相同的数据类型，单具有不同的集合类型不能构赋值
2) 给集合赋城null 值
    可以使用delete 或 trim
    也可以使用空集合赋给目表集合
    type name_varray_type is varray(4) of varchar2(10);
    name_array name_varray_type;
    name_empty name_varray_type;

    name_array:=name_varray_type('1','2');
    name_array:=name_empty;
3) 使用集合操作赋和比较集合都是10g 的内容，p176 先略过。
4 批量绑定
执行单词sql 操作能传递所有集合元素的数据。
1 forall 语句
用于insert update 和delete操作。在oracle9i 中forall 语句必须具有连续的元素
    1) using forall on insert
     declare
        type id_table_type is table of number(6)
        index by binary_integer;
        type name_table_type is table of varchar2(2)
        index by binary integer;
        id_table id_table_type;
        name_table name_table_type;
      begin
         for i in 1..10 loop
           id_table(i):=i;
           name_table(i):='Name'||to_char(i);
         end loop;
         forall i in 1..id_table.count
           insert into demo values(id_table(i),name_table(i));
      end;
     2)using forall on using update
       forall i in 1..id_table.count
           upate demo set name:=name_table(i)
              where id:=id_table(i);
     3)using forall on using delete
        forall i in 1..id_table.count
            delete from demo where id:=id_table(i);
     4) using forall on part of the collection
        for i in1..10 loop
          id_table(i):=i;
          name_table(i):="name"||to_char(i);
        end loop;
        forall i in 8..10 l
           insert into demo values(id_table(i),name_table(i));
   2 bulk collect
     is fit for select into ,fetch into and dml clause
     1) using bulk collect
      declares
        type emp_table_type is table of emp%rowtype
         index by binary_integer;
        emp_table emp_table_type;
      begin
         select * bulk collect into emp_table
          from emp where deptno=&no;
         for i in 1..emp_tablee.count loop
            dbms_output.put_line(emp_table(i).ename);
         end loop;
      2) 在dml 的返回字句使用bulk collect 字句
         declare
          type ename_table_type is table of emp.ename%type;
           ename_table ename_table_type;
          begin
             deletee from emp where deptno=&no
             returning ename bulk_collect into ename_table;
          for i in 1..ename_table.count loop
            dbms_output.put(ename_table(i));
          end loop;
        end;
          end;
      end;

康文 2006-10-11 14:44 发表评论

advanced subquery

康文 — Wed, 11 Oct 2006 06:43:00 GMT

1 subquery: is a select statement embedded in other sql statement.
.the subquery execute (inner query) once before the main query
.the result of the subquery is used by the main query.
2 pairwise comarison subquery
select * from employee
where (manager_id,department_id) in
          (select manager_id,department_id
           from employees
           where employee_id in (178,174))
and employee_id not in (178,174);
nonpairwise comparison subquery
select employee_id,manager_id,department_id
from employee
where manager_id in
                  (select manager_id
                   from employees
                   where employee id in (174,141))
and department_id in
                   (select department_id
                    from employees
                    where employee_id in (174,141))
and employ_id not in (174,141);
                  )
3 using a subquery in the from clause
select a.last_name,a,salary,b.slaavg
from employees a ,(select department_id,
                      avg(salary) salavg
                      from   employees
                      group by department_id) b
   where a.department_id=b.department_id
   and a.salary>b.salavg;
4 scalar subquery expressions
. a scalar subquery expression is a subquery that return exactly on column value from one row
. in oracle8i scalar subqueries can be used in condition and expression part and all clause.
1) sclaar subqueries in casse expression
   select employee_id ,last_name,
   (case
    when department_id=
          (select department_id from departments
          where location_id=1800)
    then 'canada'
    else 'usa'
   end) location
from employees
   2)scalar subqueries in order by clasue
   select employee_id,last_name
   from employees e
   order by (select department_name
             from departments d
             where e.department_id=d.department);
4 correlated subqueries
   the wubquery references a column form a table in the parment query
   select column1,solumn2....
   from table1 outer
   where column1 operator
                         (select column1,column2
                          from table2
                          where expr1=out.expr2);
e.g 1
   select last_name,salary,department_id
   from employees outer
   where salary>
               (select avg(salary)
                from employees
                where department_id=
                   outer.department_id);
               )
   e.g 2
    display details of those employees who have switched jobs at lease twice
    select e.employee_id,last_name,e.job_id
    from employees e
    where 2<=(select count(*)
              from job_history
              where employee_id=e.employee_id);
6 using the exists operator
. the exists operator tests for existencee of rows in the results set of the subquery
. if a subquery row value id found:
     the search does not continue in the inner query
     the condition is flagged true
.if a subquery row value is not fount
     the condition is flagged fasle
     the search continues in the inner query
e.g
    find employees who have at least one person reporting to them
    select employee_id,last_name,job_id,department_id
    from employees outer
    where exists (select count(*)
                 from employees
                 where manager_id=outer.employee_id);
not exist.
7 corelated update
    use a correlated subquery to update rows in on table based on rows from another table
   e.g
    --denormalize the employees table by adding a column to store the department name
    alter table employees
    add(department_name varchar2(14));
   --populate the table by using a correlated update
    update employees e
    set department_name=
                       (select department_name
                        from departments d
                        where e.departmentid=d.department);
8 correlated delete
    delete test1 t1
    where ster_id in(select ster_id form sales t2 where t.ster_id=t2.ster_id);
9 using the with clause ,you can use the same query block in a a select statement when it cocurs more than once within a complex query
the with clause retrieves the results of a query block and stores it in the user's the user's templary tablespace
the with clause improves performance.
e.g
   with
   dept_costs as(
    select d.department_name,sum(e.salary) as dept_total
    from employee e,departments d
    where e,department_id=d.department_id
    group by d.department_name),
   avg_cost as(
     select sum(dept_total)/count(*) as dept_avg
     from dept_cost)
select *
from dept_costs
where dept_total>(select dept_avg
                    from afb_cost)
order by department_name;

康文 2006-10-11 14:43 发表评论