Sql 如何从联接表中选择数据作为表类型?
我想构建一个非标准化视图来处理表类型的引用数据Sql 如何从联接表中选择数据作为表类型?,sql,database,oracle,oracle11g,Sql,Database,Oracle,Oracle11g,我想构建一个非标准化视图来处理表类型的引用数据 create table reftab (id number, name varchar2(40), details varchar2(1000)); / create table basictab (id number, name varchar2(300), contract varchar2 (20)); / create or replace type reftype is object (id number, name varchar2(
create table reftab (id number, name varchar2(40), details varchar2(1000));
/
create table basictab (id number, name varchar2(300), contract varchar2 (20));
/
create or replace type reftype is object (id number, name varchar2(40), details varchar2(1000));
/
create or replace type reftypetab as table of reftype;
/
insert into basictab values (1, 'aaa', 'c1');
insert into basictab values (2, 'aab', 'c1');
insert into basictab values (3, 'aaa', 'c2');
insert into basictab values (4, 'aaa', 'c3');
insert into reftab values (1, 'asd', 'aaa');
insert into reftab values (1, 'asg', 'ass');
insert into reftab values (1, 'ash', 'add');
insert into reftab values (1, 'asf', 'agg');
insert into reftab values (3, 'asd', 'aaa');
insert into reftab values (3, 'ad', 'aa');
insert into reftab values (4, 'asd', 'aaa');
insert into reftab values (4, 'as', 'a');
insert into values (4, 'ad', 'aa');
/
有了这些数据,我希望视图中包含4行basictab
,另外还有一列reftypetab
,并包含id
上连接的所有ref数据
我知道我可以通过以下方式获得:
CREATE OR REPLACE FUNCTION pipef (p_id IN NUMBER) RETURN reftypetab PIPELINED AS
BEGIN
FOR x IN (select * from reftab where id = p_id) LOOP
PIPE ROW(reftype(x.id, x.name, x.details));
END LOOP;
RETURN;
END;
/
SELECT id, pipef(id)
FROM reftab
group BY id;
/
但是没有函数有更好的方法得到结果吗?进一步的研究给了我另一种方法:
SELECT id, CAST(COLLECT(reftype(r.id, r.name, r.details)) AS reftypetab) AS customer_ids
FROM reftab r group by id;
这看起来好多了,但我还是想问问是否还有其他方法可以做到这一点
编辑
也许这并不是我想问的,但游标表达式可以给出类似的结果
SELECT id, cursor(select reftype(r.id, r.name, r.details) from reftab r where r.id = b.id) AS customer_ids
FROM basictab b;
您当前的设置得到:
SELECT id, pipef(id) as result
FROM reftab
group BY id;
ID RESULT(ID, NAME, DETAILS)
---------- ------------------------------------------------------------------------------------------------------------------------
1 REFTYPETAB(REFTYPE(1, 'asd', 'aaa'), REFTYPE(1, 'asg', 'ass'), REFTYPE(1, 'ash', 'add'), REFTYPE(1, 'asf', 'agg'))
4 REFTYPETAB(REFTYPE(4, 'asd', 'aaa'), REFTYPE(4, 'as', 'a'), REFTYPE(4, 'ad', 'aa'))
3 REFTYPETAB(REFTYPE(3, 'asd', 'aaa'), REFTYPE(3, 'ad', 'aa'))
您可以使用以下方法来简化:
select id, cast(collect(reftype(id, name, details)) as reftypetab) as result
from reftab
group by id;
ID RESULT(ID, NAME, DETAILS)
---------- ------------------------------------------------------------------------------------------------------------------------
1 REFTYPETAB(REFTYPE(1, 'asd', 'aaa'), REFTYPE(1, 'asf', 'agg'), REFTYPE(1, 'ash', 'add'), REFTYPE(1, 'asg', 'ass'))
3 REFTYPETAB(REFTYPE(3, 'asd', 'aaa'), REFTYPE(3, 'ad', 'aa'))
4 REFTYPETAB(REFTYPE(4, 'asd', 'aaa'), REFTYPE(4, 'ad', 'aa'), REFTYPE(4, 'as', 'a'))
如果您还需要basictab
中的信息,您可以使用:
谢谢,这就是我刚才发现的。看起来好多了。顺便问一下,你对这种结构有经验吗?读取数据的速度是否比执行外部联接慢得多?我想collect/multiset将比您自己的函数快,但还没有测试过速度。这里是一些比较链接。Multiset似乎更快。但另一个问题是:声明并不完全正确same@Kacper-谢谢,不过我不确定这是否是OP的意思。我以前读过那篇文章,但忘记了它为collect创建的额外类型。如果目的是合并两个表中的数据,那么multiset就是一种方法。
select bt.id, bt.name,
cast(multiset(select reftype(rt.id, rt.name, rt.details)
from reftab rt where rt.id = bt.id) as reftypetab) as result
from basictab bt;
ID NAME RESULT(ID, NAME, DETAILS)
---------- ---------- ------------------------------------------------------------------------------------------------------------------------
1 aaa REFTYPETAB(REFTYPE(1, 'asd', 'aaa'), REFTYPE(1, 'asg', 'ass'), REFTYPE(1, 'ash', 'add'), REFTYPE(1, 'asf', 'agg'))
2 aab REFTYPETAB()
3 aaa REFTYPETAB(REFTYPE(3, 'asd', 'aaa'), REFTYPE(3, 'ad', 'aa'))
4 aaa REFTYPETAB(REFTYPE(4, 'asd', 'aaa'), REFTYPE(4, 'as', 'a'), REFTYPE(4, 'ad', 'aa'))