从 Oracle 函数返回多个值

Posted 2023-03-31

【中文标题】从 Oracle 函数返回多个值

【英文标题】：Return Multiple Values from Oracle Function

【发布时间】：2019-07-08 13:21:52

【问题描述】：

我想创建一个函数，它将多行返回到一个对象类型的表中。

我已经创建了一个对象和一个嵌套表对象，现在当我运行该函数时出现一个错误，提示

PL/SQL：忽略 SQL 语句 PL/SQL: ORA-00947: 没有足够的值

-- Object type creation
create or replace type test_object_sn as object
(
    column_1 varchar2(30),
    column_2 varchar2(30),
    column_3 number 
);


-- Table of object
create or replace type test_otable_sn as table of test_object_sn; 

-- function (where I get an error)
create or replace function load_test_object_sn
return test_otable_sn
as  
    details test_otable_sn;
begin
    with ad as (select 'a', 'b', 4   from dual
    union all 
    select 'r', '5', 3  from dual
    union all
    select 'g', 's', 3  from dual)
    select * into details from ad; 

    return details;
end;

我想让 test_otable_sn 表对象加载数据，然后通过我的 load_test_object_sn 函数使用 table() 函数查询它 例如select * from table(load_test_object_sn);

【参考方案1】：

更新：

你知道如何为我有一个 sql 的情况修改这个吗 要执行的字符串变量中包含的语句？

是的，我们可以使用游标引用 (SYS_REFCURSOR) 和 OPEN/FETCH/CLOSE 来代替 CURSOR 和 CURSOR FOR LOOP。

语法是 OPEN <cursor-reference> FOR <string-containing-sql-statement> 。见下文。

CREATE OR REPLACE FUNCTION load_test_object_sn
RETURN test_otable_sn
AS  
  details test_otable_sn := test_otable_sn();

  -- Variable stores SQL statement for cursor
  l_sql CLOB :=
    q'[with ad as (
         select 'a' column_1, 'b' column_2, 4 column_3 from dual union all
         select 'r', '5', 3  from dual union all 
         select 'g', 's', 3  from dual
       )
       select *
         from ad]';

  -- Cursor reference allows us to open cursor for SQL statement above
  rc SYS_REFCURSOR;

  -- Define object instance to store each row fetched from the cursor
  l_obj test_object_sn := test_object_sn(NULL, NULL, NULL);

  i PLS_INTEGER := 1;
BEGIN

  -- Explicitly open, fetch from, and close the cursor
  OPEN rc FOR l_sql;
  LOOP
    FETCH rc INTO l_obj.column_1, l_obj.column_2, l_obj.column_3;
    EXIT WHEN rc%NOTFOUND;
    details.extend();
    details(i) := test_object_sn(l_obj.column_1, l_obj.column_2, l_obj.column_3);
    i := i + 1;
  END LOOP;
  CLOSE rc;

  RETURN details;
END;

原答案：

不幸的是，不能以这种方式将 SELECT * INTO 与集合一起使用，所以这里有另一种填充表的方法：

create or replace function load_test_object_sn
return test_otable_sn
as  
    details test_otable_sn := test_otable_sn();
    cursor c_ad is
    with ad as (select 'a' column_1, 'b' column_2, 4 column_3   from dual
    union all 
    select 'r', '5', 3  from dual
    union all
    select 'g', 's', 3  from dual)
    select * from ad;
    i pls_integer := 1;

begin

   for ad_rec in c_ad loop     
      details.extend();
      details(i) := test_object_sn(ad_rec.column_1, ad_rec.column_2, ad_rec.column_3);
      i := i + 1;
   end loop;

    return details;
end;
/

输出：

SQL> SELECT * FROM TABLE(load_test_object_sn);

COLUMN_1   COLUMN_2     COLUMN_3
---------- ---------- ----------
a          b                   4
r          5                   3
g          s                   3

【讨论】：

谢谢这个作品，你知道如何修改这个场景，我有一个包含在字符串变量中的sql语句来执行吗？