PLSQL基本语法介绍

---PL/SQL语法结构----
declare
v_name varchar2(20):='刘亦菲';
v_empno number:='123123';
v_age constant number:='23';
V_ename myemp.ename%type:='刘涛';
begin
dbms_output.put_line(v_name);
select ename into v_ename from myemp where empno='7788';
dbms_output.put_line(v_ename);
end;
----条件语句------
declare
v_age number(3):=#
begin
if v_age<18 then
dbms_output.put_line('未成年');
elsif v_age>18 and v_age<60 then
dbms_output.put_line('成年人');
else
dbms_output.put_line('老年人');
end if;
end;
---循环------
declare
i number(3):=1;
begin
loop
if i>100 then exit; end if;
dbms_output.put_line(i);
i:=i+1;
end loop;
end;

---循环----while----
declare
n number(3):=1;
begin
while n<100
loop
dbms_output.put_line(n);
n:=n+1;
end loop;
end;
---循环----for----
declare
i number(3):=1;
begin
for i in 1..100
loop
dbms_output.put_line(i);
end loop;
end;
---游标---cursor---
declare
cursor c_emp is select * from myemp;
c_row myemp%rowtype;
begin
open c_emp;
loop
fetch c_emp into c_row;
exit when c_emp%notfound;
dbms_output.put_line(c_row.ename||c_row.empno);
end loop;
close c_emp;
end;
---游标---带参数的cursor------
declare
cursor c_myemp(dpno myemp.deptno%type) is select * from myemp where deptno=dpno;
c_row myemp%rowtype;
begin
open c_myemp(30);
loop
fetch c_myemp into c_row;
exit when c_myemp%notfound;
update myemp set sal=sal+10000 where empno=c_row.empno;
end loop;
close c_myemp;
end;

select * from myemp where deptno='30';
---exception-----
declare
age number(3):=&age;
m number(1):=&m;
begin
age:=age/m;
exception
when zero_divide then
dbms_output.put_line('不能被0除');
end;
delcare

declare
---procedure---存储过程--------
create or replace procedure p_myemp(eno myemp.empno%type) is
myename myemp.ename%type;
begin
select ename into myename from myemp where empno=eno;
dbms_output.put_line(myename);
end;
call p_myemp(7788);

begin
p_myemp(7788);
end;
--procedure---带有out的存储过程----
create or replace procedure p_out(eno myemp.empno%type,yearsal out number) as
begin
select sal*12+nvl(comm,0) into yearsal from myemp where empno=eno;
dbms_output.put_line(yearsal);
end;

declare
yearsal number;
begin
p_out(7788,yearsal);
end;
----function---存储函数--
create or replace function func_myemp(eno number) return number is
year_sal number(7);
begin
select sal*12+nvl(comm,0) into year_sal from myemp where empno=eno;
return year_sal;
end;

declare
year_sal number;
begin
year_sal:=func_myemp(7788);
dbms_output.put_line(year_sal);
end;

begin
dbms_output.put_line(func_myemp(7788));
end;
-----------字段的截取----
select ename from myemp;
select  substr(ename,length(ename)-2) from myemp;
select  substr(ename,2) from myemp;
select * from myemp;
select t.*,rownum r from (select t1.*,rownum r from (select * from myemp order by sal) t1) t order by t.r desc;
--------触发器---trigger------
create or replace trigger myemp_trigger

before
insert or update or delete
on myemp

declare
today varchar2(30);
begin
select to_char(sysdate,'yyyy-mm-dd') into today from dual;
if today='2016-11-19' then
raise_application_error(-20001,'今天不能操作员工表!');
end if;
end;

insert into myemp(empno,ename,deptno) values(1111,'tom',30);
----触发器的另一个作用----数据备份-----------
create table myemp_bak(
bid number,
oldsal number,
newsal number,
alterdate date,
constraint primary_key primary key(bid)
);

create or replace trigger myemptrigger
after
update of sal
on myemp
for each row
begin
insert into myemp_bak values(mysequence.nextval,:old.sal,:new.sal,sysdate);
end;

update myemp set sal=sal+10000 where empno='7499';

select * from myemp;
select * from myemp_bak;
delete from myemp_bak;
-----数据恢复----------
create table myemp_bak_bak as
select * from myemp as of TIMESTAMP
to_timestamp('20161119 202300','yyyymmdd hh24miss');

select * from myemp_bak_bak;
select * from myemp;
drop table myemp_bak_bak;
delete from myemp;
-------------练习题-------------
declare
emp_rec myemp%rowtype;
begin

select * into emp_rec from myemp where empno=7788;

dbms_output.put_line(emp_rec.ename||'的薪水是'||emp_rec.sal);

end;
-----------数据恢复-------------------

insert into MYEMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)
values (7369, 'SMITH', 'CLERK', 7902, to_date('17-12-1980', 'dd-mm-yyyy'), 800, null, 20);
insert into MYEMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)
values (7499, 'ALLEN', 'SALESMAN', 7698, to_date('20-02-1981', 'dd-mm-yyyy'), 31600, 300, 30);
insert into MYEMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)
values (7521, 'WARD', 'SALESMAN', 7698, to_date('22-02-1981', 'dd-mm-yyyy'), 21250, 500, 30);
insert into MYEMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)
values (7566, 'JONES', 'MANAGER', 7839, to_date('02-04-1981', 'dd-mm-yyyy'), 2975, null, 20);
insert into MYEMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)
values (7654, 'MARTIN', 'SALESMAN', 7698, to_date('28-09-1981', 'dd-mm-yyyy'), 21250, 1400, 30);
insert into MYEMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)
values (7698, 'BLAKE', 'MANAGER', 7839, to_date('01-05-1981', 'dd-mm-yyyy'), 22850, null, 30);
insert into MYEMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)
values (7782, 'CLARK', 'MANAGER', 7839, to_date('09-06-1981', 'dd-mm-yyyy'), 12450, null, 10);
insert into MYEMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)
values (7788, 'SCOTT', 'ANALYST', 7566, to_date('19-04-1987', 'dd-mm-yyyy'), 3000, null, 20);
insert into MYEMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)
values (7839, 'KING', 'PRESIDENT', null, to_date('17-11-1981', 'dd-mm-yyyy'), 15000, null, 10);
insert into MYEMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)
values (7844, 'TURNER', 'SALESMAN', 7698, to_date('08-09-1981', 'dd-mm-yyyy'), 21500, 0, 30);
insert into MYEMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)
values (7876, 'ADAMS', 'CLERK', 7788, to_date('23-05-1987', 'dd-mm-yyyy'), 1100, null, 20);
insert into MYEMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)
values (7900, 'JAMES', 'CLERK', 7698, to_date('03-12-1981', 'dd-mm-yyyy'), 20950, null, 30);
insert into MYEMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)
values (7902, 'FORD', 'ANALYST', 7566, to_date('03-12-1981', 'dd-mm-yyyy'), 3000, null, 20);
insert into MYEMP (empno, ename, job, mgr, hiredate, sal, comm, deptno)
values (7934, 'MILLER', 'CLERK', 7782, to_date('23-01-1982', 'dd-mm-yyyy'), 11300, null, 10);
commit;