n 在客户端输出helloworld
set serveroutput on;//默认是off，设成on是让Oracle可以在客户端输出数据
begin
dbms_output.put_line('helloworld');
end;
/
n 变量的赋值与输出
declare
v_name varchar2(20);//声明变量v_name变量的声明以v_开头
begin
v_name := 'myname';
dbms_output.put_line(v_name);
end;
/
n pl/sql对于异常的处理(除数为0)
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;
/
n 基本变量类型
binary_integer:整数，主要用来计数而不是用来表示字段类型。比number效率高
number:数字类型
char:定长字符串
varchar2：变长字符串
date：日期
long：字符串，最长2GB
boolean：布尔类型，可以取值true，false，null//最好给一初值
变量的声明，使用 '%type'属性
declare
v_empno number(4);
v_empno2 emp.empno%type; // v_empno2的类型和emp表的empno字段的类型一样
v_empno3 v_empno2%type; // v_empno3的类型和变量v_empno2的类型一样
begin
dbms_output.put_line('Test');
end;
/
//使用%type属性，可以使变量的声明根据表字段的类型自动变换，省去了维护的麻烦，而且%type属性，可以用于变量身上
n table变量类型(数组)
declare
//定义一种数组类型，内容的类型是emp.empno%type，下标类型为binary_integer
type type_table_emp_empno is table of emp.empno%type index by binary_integer;
//声明一个数组变量
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;
n record变量类型（结构体）
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;
n 使用%rowtype声明record变量
declare
v_temp dept%rowtype;//结构体里的变量就是dept表的字段
begin
v_temp.deptno := 50;
v_temp.dname := 'aaa';
v_temp.loc := 'bj';
dbms_output.put_line(v_temp.deptno || ' ' || v_temp.dname);
end;
n select语句
必须且只能返回一条记录
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;
n 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;
n 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;
select count(*) into v_count from emp2;
//sql是一个关键字，rowcount是sql的一个属性。
dbms_output.put_line(sql%rowcount || '条记录被影响');
commit;
end;
n DDL语言，数据定义语言
begin
execute immediate 'create table t (nnn varchar2(20) default ''aaa'')';
end;
n 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;
n 循环语句
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;
n 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;
n 日志程序
--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;
n 游标
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;
n 带参数的游标
declare
cursor c (v_deptno emp.deptno%type, v_job emp.job%type)//声明形参
is
select ename, sal from emp where deptno = v_deptno and job = v_job;
begin
for v_temp in c(30,'CLERK') //v_temp不需要声明
loop
dbms_output.put_line(v_temp.ename);
end loop;
end;
n 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;
n 存储过程
存储过程出现编译错误，用show errors命令查看出错信息。
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;
n 带参数的存储过程
//in代表该参数为传入参数，out代表该参数为传出参数。不写默认为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;
--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;
n 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；
n 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//触发条件
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;
-----------
create or replace trigger trig
after insert or update or delete on emp2 for each row//每更新一行就会触发一次
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;
-----------
用这种方法可以修改外键约束的字段。
create or replace trigger trig
after update on dept for each row
begin
//NEW代表操作后的记录，OLD代表操作前的记录
update emp2 set deptno = :NEW.deptno where deptno = :OLD.deptno;
end;
n 树状结构的存储和展示
create table article
(
id number primary key,
cont varchar2(4000),
pid number,--父id
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;
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