如何在SELECT FROM语句中使用表类型？

Question

这个问题或多或少与此相同

在包头中:
声明以下行类型:

  TYPE exch_row IS RECORD(
    currency_cd VARCHAR2(9),
    exch_rt_eur NUMBER,
    exch_rt_usd NUMBER);

而这个表类型:

  TYPE exch_tbl IS TABLE OF exch_row INDEX BY BINARY_INTEGER;

添加了一个变量:

exch_rt exch_tbl;

在包体中:
用一些数据填充此表变量.

在包体中的过程中:
我想使用以下语句:

CURSOR c0 IS
  SELECT i.*, rt.exch_rt_eur, rt.exch_rt_usd
  FROM item i, exch_rt rt
  WHERE i.currency = rt.exchange_cd

如何在Oracle中执行此操作？

---

笔记

实际上我正在寻找MSSQL中的"表变量"解决方案:

DECLARE @exch_tbl TABLE
(
  currency_cd VARCHAR(9),
  exch_rt_eur NUMBER,
  exch_rt_usd NUMBER)
)

并在我的StoredProcedure中使用此表变量.

Answer 1

在SQL中,您只能使用在模式级别定义的表类型(不在包或过程级别),并且无法在模式级别定义索引表(关联数组).所以 - 你必须像这样定义嵌套表

create type exch_row as object (
    currency_cd VARCHAR2(9),
    exch_rt_eur NUMBER,
    exch_rt_usd NUMBER);

create type exch_tbl as table of exch_row;

然后你可以在带有TABLE运算符的SQL中使用它,例如:

declare
   l_row     exch_row;
   exch_rt   exch_tbl;
begin
   l_row := exch_row('PLN', 100, 100);
   exch_rt  := exch_tbl(l_row);

   for r in (select i.*
               from item i, TABLE(exch_rt) rt
              where i.currency = rt.currency_cd) loop
      -- your code here
   end loop;
end;
/

Answer 2

在Oracle 12C之前,您无法从PL/SQL定义的表中进行选择,只能从基于SQL类型的表中进行选择,如下所示:

CREATE OR REPLACE TYPE exch_row AS OBJECT(
currency_cd VARCHAR2(9),
exch_rt_eur NUMBER,
exch_rt_usd NUMBER);


CREATE OR REPLACE TYPE exch_tbl AS TABLE OF exch_row;

在Oracle 12C中,现在可以从包规范中定义的PL/SQL表中进行选择.

Answer 3

您无法在包内的单个查询中执行此操作-您无法混合使用SQL和PL / SQL类型，并且需要按照Tony，Marcin和Thio所说的在SQL层中定义类型。

如果您确实希望在本地完成此操作，并且可以通过VARCHAR而不是BINARY_INTEGER索引表类型，则可以执行以下操作：

-- dummy ITEM table as we don't know what the real ones looks like
create table item(
    item_num number,
    currency varchar2(9)
)
/   

insert into item values(1,'GBP');
insert into item values(2,'AUD');
insert into item values(3,'GBP');
insert into item values(4,'AUD');
insert into item values(5,'CDN');

create package so_5165580 as
    type exch_row is record(
        exch_rt_eur number,
        exch_rt_usd number);
    type exch_tbl is table of exch_row index by varchar2(9);
    exch_rt exch_tbl;
    procedure show_items;
end so_5165580;
/

create package body so_5165580 as
    procedure populate_rates is
        rate exch_row;
    begin
        rate.exch_rt_eur := 0.614394;
        rate.exch_rt_usd := 0.8494;
        exch_rt('GBP') := rate;
        rate.exch_rt_eur := 0.9817;
        rate.exch_rt_usd := 1.3572;
        exch_rt('AUD') := rate;
    end;

    procedure show_items is
        cursor c0 is
            select i.*
            from item i;
    begin
        for r0 in c0 loop
            if exch_rt.exists(r0.currency) then
                dbms_output.put_line('Item ' || r0.item_num
                    || ' Currency ' || r0.currency
                    || ' EUR ' || exch_rt(r0.currency).exch_rt_eur
                    || ' USD ' || exch_rt(r0.currency).exch_rt_usd);
            else
                dbms_output.put_line('Item ' || r0.item_num
                    || ' Currency ' || r0.currency
                    || ' ** no rates defined **');
            end if;
        end loop;
    end;
begin
    populate_rates;
end so_5165580;
/

因此，在循环中，无论您希望在哪里使用它，都r0.exch_rt_eur可以使用exch_rt(r0.currency).exch_rt_eur，而USD则相同。从匿名块进行测试：

begin
    so_5165580.show_items;
end;
/

Item 1 Currency GBP EUR .614394 USD .8494
Item 2 Currency AUD EUR .9817 USD 1.3572
Item 3 Currency GBP EUR .614394 USD .8494
Item 4 Currency AUD EUR .9817 USD 1.3572
Item 5 Currency CDN ** no rates defined **

根据Stef发布的答案，根本不需要将其包装在包装中。insert声明可以达到相同的结果。假设EXCH持有其他货币对欧元的汇率，包括美元，汇率为currency_key=1：

insert into detail_items
with rt as (select c.currency_cd as currency_cd,
        e.exch_rt as exch_rt_eur,
        (e.exch_rt / usd.exch_rt) as exch_rt_usd
    from exch e,
        currency c,
        (select exch_rt from exch where currency_key = 1) usd
    where c.currency_key = e.currency_key)
select i.doc,
    i.doc_currency,
    i.net_value,
    i.net_value / rt.exch_rt_usd AS net_value_in_usd,
    i.net_value / rt.exch_rt_eur as net_value_in_euro
from item i
join rt on i.doc_currency = rt.currency_cd;

使用价值19.99英镑和25.00澳元的商品，您可以获得detail_items：

DOC DOC_CURRENCY NET_VALUE         NET_VALUE_IN_USD  NET_VALUE_IN_EURO
--- ------------ ----------------- ----------------- -----------------
1   GBP          19.99             32.53611          23.53426
2   AUD          25                25.46041          18.41621

如果您希望货币的东西更可重用，则可以创建一个视图：

create view rt as
select c.currency_cd as currency_cd,
    e.exch_rt as exch_rt_eur,
    (e.exch_rt / usd.exch_rt) as exch_rt_usd
from exch e,
    currency c,
    (select exch_rt from exch where currency_key = 1) usd
where c.currency_key = e.currency_key;

然后使用其中的值插入：

insert into detail_items
select i.doc,
    i.doc_currency,
    i.net_value,
    i.net_value / rt.exch_rt_usd AS net_value_in_usd,
    i.net_value / rt.exch_rt_eur as net_value_in_euro
from item i
join rt on i.doc_currency = rt.currency_cd;