Oracle PL/SQL入门语法点


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;

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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

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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

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/*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

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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

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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

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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

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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

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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

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begin

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

end;

--if语句

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--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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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