PL/SQL常用语句

面向过程的语言

--最简单的语句块

//:=代表赋值; =代表相等

set serveroutput on;

begin

dbms_output.put_line('helloworld!');

end;

--简单PL/SQL语句块

declare

v_name varchar2(20);

begin

v_name := 'myname';

dbms_output.put_line(v_name);

end;

--完整语句块组成

declare

v_num number := 0;

begin

v_num := 2/v_num;

dbms_output.put_line(v_num);

exception

when others then

dbms_output.put_line('error');

end;

--变量声明规则

1，变量名不能使用保留字，如 from,select等

2，第一个字符必须是字母

3，变量名最多包含三十个字符

4，不要与数据库的表或者列同名

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

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 true,false 和 null值

declare

v_temp number(1);

v_count binary_integer := 0;

v_sal number(7,2) := 4000.00;

v_date date := sysdate;

v_date2 date ;

v_pi constant number(3,2) := 3.14;

v_valid boolean := false;

v_name varchar2(20) not null := 'myname';

begin

v_date2 := to_date('1999-08-12 12:23:38','YYYY-MM-DD HH24:MI:SS');

dbms_output.put_line('v_temp value:' || v_count);

end;

--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;

符合变量

--table 变量类型//相当于Java中的数组

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//相当于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 := '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;

DML语句

--使用select 语句//必须和into一起使用,必须有且只有一条记录返回

declare

v_ename emp.ename%type;

v_sal emp.sal%type;

begin

select ename,sal into v_ename,v_sal from emp when empno = 7369;

dbms_output.put_line(v_ename || ' ' || v_sal);

end;

declare

v_emp emp%rowtype;

begin

select * into v_emp from emp when ename = 7369;

dbms_output.put_line(v_emp.ename);

end;

--insert 语句

declare

v_deptno 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;

end;

--update语句

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;//一条记录被影响

--select count(*) into v_count from emp2;//一条记录被影响

dbms_output.put_line(sql%rowcount || '条记录被影响');//sql代表刚刚执行的那条语句，rowcount代表sql影响的记录条数

commit;

end;

DDL语句//执行DDL语句需要加 execute immediate

begin

execute immediate 'create table T (nnn varchar2(20) default ''aaa'')';//''为两个单引号

end;

--if语句

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;

--循环语句

declare

i binary_integer := 1;

begin

loop//相当于Java中的do-while循环

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 //相当于Java中的while循环

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//reverse代表逆序

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.put_line('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('没数据');

end;

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;//SQLCODE为关键字，出错代码

v_errmsg := SQLERRM;//SQLERRM为关键字，出错信息

insert into errorlog values (seq_errorlog_id.nextval,v_errcode,v_errmsg,sysdate);

commit;

end;

--cursor(游标)//重点掌握

declare

cursor c is

select * from emp;

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;

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//最常用

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;

--v_temp c%rowtype;

begin

for v_emp in c(30,'CLERK') loop

dbms_output.put_line(v_emp.ename);

end loop;

end;

--可更新的游标

declare//最常用

cursor c is

select * from emp for update;

--v_temp c%rowtype;

begin

for v_emp 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;

end;

--存储过程(stored procedure)

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;

elsif (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;

调用过程方法一

begin

p;

end;

调用过程方法二

exec p;

--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;

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(trigger)

create table emp2_log

(

uname varchar2(20),

action varchar2(10),

atime date

);

create or replace trigger trig

after insert or delete or update 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;

update emp2 set sal = sal*2 where deptno = 30;

select * from emp2_log;

update emp2 set deptno = 99 where deptno = 10;//此语句出错,违反完整约束条件

drop trigger trig;

create or replace trigger trig//附加功能,不常用

after update on dept for each row

begin

update emp set deptno = :NEW.deptno where deptno = :OLD.deptno;

end;

select * from emp;

rollback;

--树状结构的存储和展示

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)

);

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,'怎么没有可能',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);

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.id,v_level + 1);

end if;

end loop;

end;