oracle 管道化表函数(Pipelined Table) [转]

最新推荐文章于 2023-08-10 15:27:32 发布

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最新推荐文章于 2023-08-10 15:27:32 发布

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文章标签：数据库

原文链接：http://www.cnblogs.com/RobotTech/archive/2011/01/14/1935771.html

介绍Oracle管道化表函数的创建及使用方法，包括定义类型、创建表类型、创建表函数等步骤，并提供多个实例演示其功能。

http://log-cd.javaeye.com/blog/411123

关键字: oracle pipelined table

在实际的应用中，为了让PL/SQL 函数返回数据的多个行，必须通过返回一个 REF CURSOR 或一个数据集合来完成。REF CURSOR 的这种情况局限于可以从查询中选择的数据，而整个集合在可以返回前，必须进行具体化。 9i 通过引入的管道化表函数纠正了后一种情况。表函数是返回整个行的集（通常作为一个集合）的函数，可以直接从 SQL 语句中进行查询，就好像它是一个真正的数据库表一样。管道化表函数与之相似，但是它像在构建时一样返回数据，而不是一次全部返回。管道化表函数更加有效，因为数据可以尽可能快地返回。

管道化表函数必须返回一个集合。在函数中，PIPE ROW 语句被用来返回该集合的单个元素，该函数必须以一个空的 RETURN 语句结束，以表明它已经完成。一旦我们创建了上述函数，我们就可以使用 TABLE 操作符从 SQL 查询中调用它。

例1：
Type Definition

Sql代码

CREATE OR REPLACE TYPE COLOR_HEX_CODE AS OBJECT
(
-- Attributes
colorName Varchar2(10),
colorCode varchar2(10)
-- Member functions and procedures
--member procedure <ProcedureName>(<Parameter> <Datatype>)
);

CREATE OR REPLACE TYPE COLOR_HEX_CODE AS OBJECT (   -- Attributes   colorName Varchar2(10),   colorCode varchar2(10)      -- Member functions and procedures   --member procedure <ProcedureName>(<Parameter> <Datatype>) );

Create Table Type

Sql代码

CREATE OR REPLACE TYPE COLOR_TYPE AS TABLE OF COLOR_HEX_CODE;

CREATE OR REPLACE TYPE COLOR_TYPE AS TABLE OF COLOR_HEX_CODE;

Create Table Function

Sql代码

CREATE OR REPLACE FUNCTION F_PIPELINE_TEST RETURN COLOR_TYPE PIPELINED
AS
BEGIN
PIPE ROW(COLOR_HEX_CODE('black','#000000'));
PIPE ROW(COLOR_HEX_CODE('white','#FFFFFF'));
PIPE ROW(COLOR_HEX_CODE('red','#FF0000'));
PIPE ROW(COLOR_HEX_CODE('green','#00FF00'));
PIPE ROW(COLOR_HEX_CODE('blue','#0000FF'));
RETURN;
END;

CREATE OR REPLACE FUNCTION F_PIPELINE_TEST RETURN COLOR_TYPE PIPELINED AS BEGIN     PIPE ROW(COLOR_HEX_CODE('black','#000000'));     PIPE ROW(COLOR_HEX_CODE('white','#FFFFFF'));     PIPE ROW(COLOR_HEX_CODE('red','#FF0000'));     PIPE ROW(COLOR_HEX_CODE('green','#00FF00'));     PIPE ROW(COLOR_HEX_CODE('blue','#0000FF'));     RETURN; END;

测试:

Sql代码

select * from table( f_pipeline_test );

结果：
COLORNAME COLORCODE
black #000000
white #FFFFFF
red #FF0000
green #00FF00
blue #0000FF

例2：实现split函数功能

Sql代码

CREATE OR REPLACE TYPE RESOLVE_STR IS TABLE OF VARCHAR2 (4000);

CREATE OR REPLACE TYPE RESOLVE_STR IS TABLE OF VARCHAR2 (4000);

Sql代码

CREATE OR REPLACE FUNCTION F_SPLIT
(
P_STR IN VARCHAR2,
P_DELIMITER IN varchar2
) RETURN RESOLVE_STR PIPELINED
AS
j INT := 0;
i INT := 1;
len INT := 0;
len1 INT := 0;
tmp VARCHAR2 (4000);
v_str VARCHAR2 (4000);
BEGIN
v_str := TRIM(BOTH P_DELIMITER FROM P_STR);--去掉前后的分隔符
len := LENGTH (v_str);
len1 := LENGTH(P_DELIMITER);
WHILE j < len
LOOP
j := INSTR (v_str, P_DELIMITER, i);--寻分隔符位置
IF j = 0 THEN--没有了
tmp := SUBSTR (v_str, i);
PIPE ROW (tmp);
EXIT;--结束
ELSE
tmp := SUBSTR (v_str, i, j - i);
i := j + len1;
PIPE ROW (tmp);
END IF;
END LOOP;
RETURN;
END;

CREATE OR REPLACE FUNCTION F_SPLIT     (        P_STR       IN   VARCHAR2,        P_DELIMITER IN   varchar2      ) RETURN RESOLVE_STR PIPELINED AS     j     INT := 0;     i     INT := 1;     len   INT := 0;     len1  INT := 0;     tmp   VARCHAR2 (4000);     v_str VARCHAR2 (4000); BEGIN     v_str := TRIM(BOTH P_DELIMITER FROM P_STR);--去掉前后的分隔符     len := LENGTH (v_str);     len1 := LENGTH(P_DELIMITER);      WHILE j < len       LOOP           j := INSTR (v_str, P_DELIMITER, i);--寻分隔符位置            IF j = 0 THEN--没有了               tmp := SUBSTR (v_str, i);               PIPE ROW (tmp);               EXIT;--结束           ELSE               tmp := SUBSTR (v_str, i, j - i);               i := j + len1;               PIPE ROW (tmp);           END IF;       END LOOP;      RETURN; END;

测试：

Sql代码

SELECT * FROM TABLE (F_SPLIT('-12-02-ab-cd-a0-ef-', '-'));

SELECT * FROM TABLE (F_SPLIT('-12-02-ab-cd-a0-ef-', '-'));

例3：产生6个0..49的随机数
First the quick-and-dirty solution without a pipelined function

Sql代码

select r from (
select r from (
select rownum r from all_objects where rownum < 50
) order by dbms_random.VALUE
)where rownum <= 6;

select r from (        select r from (               select rownum r from all_objects where rownum < 50                      ) order by dbms_random.VALUE               )where rownum <= 6;

pipelined function

Sql代码

CREATE OR REPLACE TYPE ARRAY AS TABLE OF NUMBER;

CREATE OR REPLACE TYPE ARRAY AS TABLE OF NUMBER;

Sql代码

CREATE OR REPLACE FUNCTION gen_numbers(n IN NUMBER DEFAULT NULL)
RETURN ARRAY PIPELINED
AS
BEGIN
FOR i IN 1 .. nvl(n,9999)
LOOP
PIPE ROW(i);
END LOOP;
RETURN;
END;

CREATE OR REPLACE FUNCTION gen_numbers(n IN NUMBER DEFAULT NULL) RETURN ARRAY PIPELINED AS   BEGIN     FOR i IN 1 .. nvl(n,9999)     LOOP     PIPE ROW(i);     END LOOP;   RETURN; END;

测试：

Sql代码

select * from (
select *
from (select * from table(gen_numbers(49))) order by dbms_random.random
)
where rownum <= 6

select * from (   select *     from (select * from table(gen_numbers(49)))  order by dbms_random.random   ) where rownum <= 6

generating that range of dates

Sql代码

select to_date('2009-5-10','yyyy-mm-dd') + column_value-1 from TABLE(gen_numbers(15));

select to_date('2009-5-10','yyyy-mm-dd') + column_value-1 from TABLE(gen_numbers(15));

Note the name of the column we used: COLUMN_VALUE. That is the default name for the column coming back from the PIPELINED function.
another example

Sql代码

CREATE OR REPLACE TYPE date_array AS TABLE OF DATE;

CREATE OR REPLACE TYPE date_array AS TABLE OF DATE;

Sql代码

CREATE OR REPLACE FUNCTION date_table(sdate DATE, edate DATE)
RETURN date_array PIPELINED AS
BEGIN
FOR i IN 0 .. (edate - sdate)
LOOP
PIPE ROW(sdate + i);
END LOOP;
RETURN;
END date_table;

CREATE OR REPLACE FUNCTION date_table(sdate DATE, edate DATE) RETURN date_array PIPELINED AS BEGIN   FOR i IN 0 .. (edate - sdate)   LOOP     PIPE ROW(sdate + i);   END LOOP;   RETURN; END date_table;

转载于:https://www.cnblogs.com/RobotTech/archive/2011/01/14/1935771.html