PL SQL笔记(三)

loop
  if credit_rating < 3 then
    ..
    exit;
  end if;
end loop;

 

select to_char(sysdate, 'YYYY-MM-DD HH24:MI:SS') from dual;
select cast(sysdate as timestamp) from dual;

复合类型数据

1.记录:

declare
  type
    emp_record_type
  is record
  (
    r_name emp.ename%type,
    r_job emp.job%type
  );
  emp_record emp_record_type;
begin
  select t.ename, t.job into emp_record from emp t where t.empno = '7369';
  dbms_output.put_line('ename = ' || emp_record.r_name || ', r_job = ' || emp_record.r_job);
end;
/ 

2.联合数组:

declare
  type
    emp_table_type
  is table of
    emp.ename%type
  index by binary_integer;
  emp_table emp_table_type;
begin
  select ename into emp_table(0) from emp where empno = '7369';
  dbms_output.put_line('ename = ' || emp_table(0));
end;
/

3.嵌套表:

嵌套表和联合数组类似，但嵌套表可以作为列的数据类型使用，而联合数组不能。

create or replace type item_type as object
(
  t_username varchar2(20),
  t_password varchar2(20),
  t_age smallint
);
declare
  type itemtable is table of item_type;
  v_table itemtable := itemtable();
begin
  v_table.extend;
  v_table(v_table.last) := item_type('dys', 'dys123', 10);
end;

利用嵌套表当表列数据类型：

create or replace type itemtable is table of Item_Type;
create table TestTable
(
  address varchar2(100),
  phoneNumber varchar2(11),
  itemList itemtable
)
nested table itemList store as itemList;

4.变长数组:
变长数组可以作为表列的数据类型或对象类型属性的数据类型，嵌套表长度没有限制，而变长数组长度有限制：

create or replace type idArray_Type as varray(100) of number;

create or replace type item_type as object
(
  v_itemCode char(10),
  v_name varchar2(20)
);

create or replace type itemArray as varray(10) of item_type;

create table TestT
(
  v_id number(8),
  items itemArray
)

pl sql 基本结构：

declare
  v_id number(8) := 10;
  v_username varchar2(20);
begin
  delete from A;
  insert into A values(v_id, 'ding', 'ding123');
  select username into v_username from A where id = v_id;
  dbms_output.put_line('v_username = ' || v_username);
  exception
    when no_data_found then
      dbms_output.put_line('no data');
end;
/

常量：

declare
  PI constant number(9) := 3.1415926;
begin
  commit;
end;

变量：

declare
  age number(3) := 26;
begin
  commit;
end;

其他类型：

emp.empno%type
emp%rowtype

分支：

if ... then

if sales > 10 then
  compute_bonus(empid);
  update payroll set pay = pay + bonus where empno = emp_id;
end if;

if .. then ... else

if trans_type = 'CR' then
  update accounts set balance = balance + debit where ...
else
  update accounts set balance = balance - debit wehre ...
end if;

if trans_type = 'CR' then
  update accounts set balance = balance - debit where ...
else
  if new_balance >= minimum_balance then
     update accounts set balance = balance - debit where ...
  else
      raise insufficient_funds;
  end if;
end if;

if .. then ...elsif

begin
  if sales > 50000 then
     bonus := 1500;
  elsif sales > 35000 then
     bonus := 500;
  else
     bonus := 100;
  end if;
  insert into payroll values(emp_id, bonus...);
end;

case语句：

case grade
  when 'A' then
     dbms_output.put_line('A');
  when 'B' then
     dbms_output.put_line('B');
  else
     dbms_output_put_line('wrong!');
end case;

搜寻式case语句：

case
  when grade = 'A' then
     dbms_output.put_line('A');
  when grade = 'B' then
    dbms_output.put_line('B');
  else
    dbms_output.put_line(''wrong!);
end case;

loop

loop
  ....
end loop;

exit(只能入到循环中，如果普通PL SQL 块要退出用return)

loop
   if a > 3 then
     ...
     exit;
   end if;
end loop;

exit .. when

loop
  fetch c1 into ...
  exit  when c1%notfound;
  ...
end loop;
close c1;

if == exit ... when

if a > 100 then
   exit;
end if;

-----------------------------------------------------------
exit when a > 100;

loop label(循环标签)

<<outer>>
loop
  ...
  loop
    ...
    exit outer when ...
  end loop;
end loop outer;

while ... loop

while a < 100 loop
  ...
  select sal into salary from emp where x = x;
  ...
  total := total + salary;
end loop;
  

其他用法:

loop
   ...
   exit when a > 10;
end loop;
--------------------------------------------
do{
} while()
---------------------------------------------
done := false;
while not done loop
  ....
 done := boolean_expression;
end loop;

for ... loop

declare
   type datelist is table of date index by binary_integer;
   dates datelist;
   k constant integer := 5;
begin
   for j in 1 .. 3 loop
       dates(j * k) := sysdate;
   end loop;
end;

select count(empno) into emp_count from emp;
for i in 1 .. emp_count loop
   ...
end loop;
-----------------------------------------------------------
<<main>>
declare
  ctr integer;
begin
   ...
   for ctr in 1 .. 25 loop
      ...
      if main.ctr > 10 then
        ...
      end if;
   end loop;
end main;

for exit

for j in 1 .. 10 loop
   fetch cl into emp_rec;
     exit when cl%notfound;
   ...
end loop;
-------------------------------------------------
<<outer>>
for i in 1 .. 5 loop
  ...
  for j in 1 .. 10 loop
      fetch cl into emp_rec;
         exit outer when cl%notfound;
      ...
   end loop;
end loop outer;

goto

declare
   done boolean;
   for i in 1 .. 10 loop
      if done then
         goto end_loop;
      end if;
      ...
     <<end_loop>>
     null;
  end loop;
endl;

declare
   my_ename char(10);
begin
   <<get_name>>
   select ename into my_ename from emp wher ...
   begin
     ...
    goto get_name;
   end;
end;

null

exception
   when zero_divide then
      rollback;
   when value_error then
      insert into errors values...
   when others then
     null;

if rating > 90 then
   compute_bonus(emp_id);
else
   null
end if;

 DCL(数据控制语句)

权限	说明
create user	创建其他用户(dba角色)
drop user	删除其他用户
select any table	查询任何用户表或视图
create any table	在任何表空间中创建表
drop any table	删除在任何表空间中所创建的表
create session	连接数据库
create table	在用户自己表空间中创建表
create view	在用户自己表空间中创建视图
create sequence	在用户自己的表空间中创建序列
create proceudre	在用业内自己表空间中创建存储过程

授权:

grant create any table to scott;

撤销授权：

revoke create any table from scott;

保存点：

savepoint a;

execute dbms_transaction.savepoint('B');

回滚保存点:

rollback to B;

exeucte dbms_transaction.rollback_savepoint('A');

回滚全部事物：

rollback;

execute dbms_transaction.rollback;