Oracle PL/SQL 语句简单用法（二）

--DDL语句
begin
  execute immediate 'create table T(nnn varchar2(20) default ''aaa'')';
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'
--注意elsif的写法
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
   declare
    i binary_integer :=1;
  begin
   loop
      dbms_output.put_line(i);
      i := i +1;
           exit when(i >= 5);
end loop;
  end;
  /

declare
   j binary_integer := 1;
begin
  while j<6 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;
/

--EXCEPTION
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;
/

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
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;
/

--循环遍历
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 emp%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;
/
--for循环遍历
declare
  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cursor
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;
/


--可更改的游标
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;
/

--存储过程
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;
/



--提交储存过程
execute p;

begin
  p;
end;
/
--带参数的存储过程
--in叫做存入，out传出(oracle没有返回值)
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;
   
    
--查看存储器编译时的异常
show error


--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;
/

--触发器
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, 'update', sysdate);
    end if;
end;
/

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

select * from emp2_log;

--触发带有条件约束的触发器
  
  create or replace trigger trig
     after update on dept
     for each row
  begin
    update emp set deptno = :NEW,deptno where deptno = :OLD.deptno;
  end;
  /


--树状结构的存储与展示

  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);
  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.isleaf = 0) then
p(v_article.id, v_level + 1);
        end if;
end loop;
  end;