动态 Pivot N 行到 N 列

如何解决动态 Pivot N 行到 N 列

我想将多行转换成列 我找到了以下代码

我的问题是，我可以在表中存储过程输出吗？

来自这个链接 https://asktom.oracle.com/pls/apex/f?p=100:11:::::P11_QUESTION_ID:4471013000346257238

代码

create table fish (

fish_id number,fish_type varchar2(3),fish_weight number);

insert into fish values (1,'COD',20);

insert into fish values(1,'HAD',30);

insert into fish values(2,45);

insert into fish values(2,'HKE',10);

insert into fish values(2,'LIN',55);

insert into fish values(3,'CTY',90);

insert into fish values (3,60);

insert into fish values (3,52);   

/

create or replace procedure go_fishing( p_cursor in out sys_refcursor )

    as

        l_query long := 'select fish_id';

    begin

        for x in (select distinct fish_type from fish order by 1 )

        loop

            l_query := l_query ||
               replace( q'|,sum(decode(fish_type,'$X$',fish_weight)) $X$|',dbms_assert.simple_sql_name(x.fish_type) );

       end loop;
   
       l_query := l_query || ' from fish group by fish_id order by fish_id';

   
       open p_cursor for l_query;

   end;

   /

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解决方法

您可以通过在存储函数（或过程）中使用 SYS_REFCURSOR 来动态旋转数据，例如

CREATE OR REPLACE FUNCTION Get_Fish_Weight_ByType RETURN SYS_REFCURSOR IS
  v_recordset SYS_REFCURSOR;
  v_sql       VARCHAR2(32767);
  v_cols      VARCHAR2(32767);
BEGIN
  SELECT LISTAGG( ''''||fish_type||''' AS "'||fish_type||'"',',' )
                 WITHIN GROUP ( ORDER BY fish_type )
    INTO v_cols
    FROM ( SELECT DISTINCT fish_type
             FROM fish );

  v_sql :='SELECT * 
             FROM fish e
            PIVOT
            (
             MAX(fish_weight) FOR fish_type IN ( '|| v_cols ||' )
            )';

  OPEN v_recordset FOR v_sql;
  DBMS_OUTPUT.PUT_LINE(v_sql);
  RETURN v_recordset;
END;
/

生成并运行以下 Select 语句

SELECT * 
  FROM fish e
 PIVOT
 (
   MAX(fish_weight) FOR fish_type IN ( 'COD' AS "COD",'CTY' AS "CTY",'HAD' AS "HAD",'HKE' AS "HKE",'LIN' AS "LIN" )
 )

Demo for the produced SQL statement

然后从 SQL Developer 的控制台调用创建的函数

SQL> DECLARE
    res SYS_REFCURSOR;
BEGIN
   :res := Get_Fish_Weight_ByType;
END;
/

SQL> PRINT res;