Oracle PL/SQL

PL_SQL：带有分支和循环,面向过程

匿名块：

declare(可选，声明各种变量和游标的地方)
begin(必要的，从此开始执行)
exception(抓取到异常后执行的)
end;

set serveroutput on;(默认是关闭) --最简单的PL/SQL语句块 begin dbms_output.put_line('HelloWorld!'); end; --最简单的语句块 declare v_name varchar2(20); begin v_name := 'myname'; dbms_output.put_line(v_name); end; --语句块的组成 declare v_name number := 0; begin v_name := 2/v_num; dbms_output.put_line(v_name); exception when others then dbms_output.put_line('error'); end;

--变量声明

1. 变量名不能够使用保留字，如from，select等
2. 第一个字符必须是字母
3. 变量名最多包含30个字符
4. 不要与数据库表或者列同名
5. 每一行只能声明一个变量

--常用变量类型

1. binary_integer： 整数，主要用来计数而不是用来表示字段类型，效率高
2. number： 数字类型
3. char： 定长字符串
4. varchar2： 变长字符串
5. date： 日期
6. long： 长字符串，最长2GB
7. boolean： 布尔类型，可以取值为ture、false和null值，一定要给初值，无法打印

--变量声明

declare v_temp number(1); v_count binary_integer := 0; v_sal number(7,2) := 4000.00; v_date date := sysdate; v_pi constant number(3,2) := 3.14; v_valid boolean := false; v_name varchar2(20) not null := 'MyName'; begin dbms_output.put_line('v_temp value:' || v_count); end;

--变量声明，使用%type属性

/*注释多行*/ --注释一行 declare v_empno number(4); v_empno2 emp.empno%type;--用表内字段类型声明变量类型 v_empno3 v_empno2%type;--用变量type属性声明变量类型 begin dbms_output.put_line('Test'); end;

--简单变量赋值

declare v_name varchar2(20); v_sal number(7,2); v_sal2 number(7,2); v_valid boolean := false; v_date date; begin v_name := 'MyName'; v_sal := 23.77; v_sal2 := 23.77; v_valid := (v_sal = v_sal2);--判断是否相等用= v_date := to_date('1999-08-12 12:23:30','YYYY-MM-DD HH24:MI:SS'); end;

--Table变量类型，表示一个数组

declare type type_table_emp_empno is table of emp.empno%type index by binary_integer;--首先声明一个类型 v_empnos type_table_emp_empno;--再用这个类型声明变量 begin v_empnos(0) := 7369; v_empnos(2) := 7839; v_empnos(-1) := 9999; dbms_output.put_line(v_empnos(-1));---1访问不到，0,2可以访问到 end;

--Record类型，表示一个类

declare type type_record_dept is record ( deptno dept.deptno%type, dname dept.dname%tpye, loc dept.loc%type ); v_temp type_record_dept; begin v_temp.deptno := 50; v_temp.dname := 'aaaa'; 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 := 'aaaa'; v_temp.loc := 'bj'; dbms_output.put_line(v_temp.deptno || ' ' || v_temp.dname); end;

--PL/SQL里执行select语句的话，配合into，必须返回并只能返回一条记录
--SQL语句的运用

declare v_ename emp.ename%type; v_sal emp.sal%type; begin select ename,sal into v_ename,v_sal from emp where empno = 7369; dbms_output.put_line(ename || ' ' || 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; declare v_deptno dept.deptno%type := 50; v_dname dept.dname%type := 'aaaa'; v_loc dept.loc%type := 'bj'; begin insert into dept2 values(v_deptno,v_dname,v_loc); commit;--别忘了!!! end; select * from dept2; 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');//sql,关键字，代表刚刚执行的sql程序 end;

--PL/SQL执行DDL语句,需要加execute immediate

begin execute immediate 'create table T(nnn varchar2(20) default ''aaaa'')'; end;

--if语句

--取出7369的薪水，如果<1200，则输出'low'，如果<2000则输出'middle'，否则输出'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 --elsif没e dbms_output.put_line('midddle'); else dbms_output.put_line('high'); end if; end;

--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 deptno = 10; exception when too_many_rows then dbms_output.putline('太多记录了'); 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;

--sql程序跨数据库平台较好，PL/SQL效率高

--DBA，错误日志

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;

--游标cursor，结果集上的指针

declare cursor c is select * from emp;--只是声明游标，还未取数据 v_emp c%rowtype begin open c; fetch c into v_emp; dbms_output.put_line(v_emp.ename); close c; end; declare cursor c is select * from emp; v_emp c%rowtype; beigin open c; loop fetch c into v_emp; exit when (c%notfound); dbms_output.put_line(v_emp.ename); end loop; close c; 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; else if (v_temp.sal = 5000) then delete from emp2 where current of c; end if; end loop; commit; end;

--创建存储过程，带有名字的PL/SQL块

grant create procedure to shijin; create or replace procedure p is cursor c is select * from emp2 for update; begin for v_emp in c loop if(v_emp.deptno = 10) then update emp2 set sal = sal + 10 where current of c; else if (v_emp.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 loop; begin p; end; 或者 exec p;

--带参数的存储过程，默认是in

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; 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; select sal_tax(sal) from emp;

--触发器！！！！牢牢掌握概念

create table emp2_log ( uname varchar2(20), action varchar2(10), atime date ); grant create triger to shijin; create or replace trigger trig after insert or delete or update on emp2 --此处可以加上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; update emp2 set sal = sal*2 where deptno = 30; drop trigger trig; create or replace trigger trig after update on dept for each row begin update emp set deptno = :NEW.deptno where deptno = :OLD.deptno; end;

--树状结构数据的存储与显示

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) ) 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_articel.id,v_level + 1); end if; end loop; end; 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',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,'怎么没有可能',6,1,2); insert into article values (8,'可能性很大的',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); set serverout on; begin p(0,0); end; show error; --展示emp的树状结构