Pl/sql学习笔记2

 

--

declare

type vsal_table is
table
of emp.sal%type;

a vsal_table;

begin

--必须得初始化 并且有数量上的区分 从一开的

a:=vsal_table(1000,2000,30000);

dbms_output.put_line(a(1));

end;

 

 

--使用嵌套表的案例

--定义一个类型

create
type stu_name is
table
of
varchar2(20);

 

create
table stu (

sid
number(9),age number(2)
, sname stu_name

)nested
table sname store
as stu_name_table;

 

select
*from stu;

--此时嵌套表就已经建立好了 需要插入语句

insert
into stu values
(1,20,stu_name('cheng','zhi'));

 

--查询sname 然后遍历出来

declare

sname stu_name;

begin

select sname into sname from stu where
sid=1;

for i in sname.first..sname.last loop

dbms_output.put_line(sname(i));

end
loop;

end;

--更新数据

declare

sname1 stu_name:=stu_name('zhang','san');

begin

update stu set sname=sname1 where
sid=1;

end;

 

--变长数组 array 需要预先指定一种长度 并进行赋值

declare

type v_ename is
array(3)
of emp.ename%type;

v1 v_ename:=v_ename('aa','bb','cc');

begin

select ename into v1(2)
from emp where empno=7369;

dbms_output.put_line(v1(2));

end;

 

--常用的函数

--collectionname.method_name(arg);

--exists是否存在什么样的元素 必须传入一个number类型的数据

--count 是取集合的长度 元素的个数

--limit 返回集合的最大个数

--prior 取出当前的上一个元素

--next 下一个的下标

declare

type v_ename is
array(20)
of emp.ename%type;

v1 v_ename:=v_ename('aa','bb','cc');

begin

if v1.exists(1)
then

dbms_output.put_line(v1.count);

dbms_output.put_line(v1.limit);

dbms_output.put_line('hava');

dbms_output.put_line(v1(2));

dbms_output.put_line(v1(v1.prior(2)));

dbms_output.put_line(v1(v1.next(2)));

else

dbms_output.put_line('no');

end
if;

end;

--delete函数

declare

type vsal_table is
table
of emp.sal%type;

a vsal_table;

begin

--必须得初始化 并且有数量上的区分 从一开的

a:=vsal_table(1000,2000,30000);

dbms_output.put_line(a(1));

dbms_output.put_line(a.count);

a.delete(3);

dbms_output.put_line(a.count);

end;

--删除的时候下标不会发生变化 位置不会变化

 

--oracle 里面的批量处理的问题

create
table t1(tid number(9),tname varchar2(9));

select
*
from t1;

 

declare

type id_table is
table
of
number(9)
index
by
binary_integer;

type name_table is
table
of
varchar2(9)
index
by
binary_integer;

start_time number(10);

end_time number(10);

v_id_table id_table;

v_name_table name_table;

begin

for i in
1..10000 loop

v_id_table(i):=i;

v_name_table(i):=to_char(i);

end
loop;

start_time:=dbms_utility.get_time;

for i in
1..v_id_table.count loop

insert
into t1 values(v_id_table(i),v_name_table(i));

end
loop;

end_time:=dbms_utility.get_time;

dbms_output.put_line(end_time-start_time);

end;

 

--瞬间插入10000条记录

create
table t2(tid number(9),tname varchar2(9));

select
count(*)
from t2;

 

declare

type id_table is
table
of
number(9)
index
by
binary_integer;

type name_table is
table
of
varchar2(9)
index
by
binary_integer;

start_time number(10);

end_time number(10);

v_id_table id_table;

v_name_table name_table;

begin

for i in
1..10000 loop

v_id_table(i):=i;

v_name_table(i):=to_char(i);

end
loop;

start_time:=dbms_utility.get_time;

forall i in
1..v_id_table.count

insert
into t2 values(v_id_table(i),v_name_table(i));

 

end_time:=dbms_utility.get_time;

dbms_output.put_line(end_time-start_time);

end;

--批量处理=之更新

declare

type id_table is
table
of
number(9)
index
by
binary_integer;

type name_table is
table
of
varchar2(9)
index
by
binary_integer;

vid id_table;

vname name_table;

begin

for i in
1..100 loop

vid(i):=i;

vname(i):=to_char(i)||'name';

end
loop;

forall i in
1..vid.count

update t2 set tname=vname(i)
where tid=vid(i);

end;

 

select
*
from t2 where tname='1name';

 

--使用 bulk collect 处理批量任务

declare

type t2_table is
table
of t2%rowtype
index
by
binary_integer;

vt t2_table;

begin

select
*
bulk
collect
into vt from t2;

end;

 

--游标案例

declare

v_emp emp%rowtype;

--声明游标

cursor cur_emp is

select
*
from emp;

begin

--open cursor

open cur_emp;

loop

--fetch

fetch cur_emp into v_emp;

exit
when cur_emp%notfound;

dbms_output.put_line(v_emp.ename||' '||v_emp.sal);

end
loop;

--close cursor

close cur_emp;

end;

 

--灵活掌握

declare

type r1 is
record
(

ename emp.ename%type,

sal emp.sal%type

);

type a1 is
table
of r1 index
by
binary_integer;

a a1;

begin

select ename ,sal bulk
collect
into a from emp;

for i in a.first..a.last loop

dbms_output.put_line(a(i).ename||' '||a(i).sal);

end
loop;

end;