重构wm_concat,采用clob做为存储容器

最新推荐文章于 2024-10-24 09:51:04 发布

原创最新推荐文章于 2024-10-24 09:51:04 发布 · 897 阅读

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本文深入探讨了在大型数据集中使用SQL聚合函数进行数据汇总的方法，包括如何利用ODCIAGGREGATEINITIALIZE、ODCIAGGREGATEITERATE、ODCIAGGREGATETERMINATE和ODCIAGGREGATEMERGE四个关键函数来优化数据处理流程。通过实例演示，展示了这些函数在实现数据聚合任务时的高效性和灵活性。

--Type
CREATE OR REPLACE TYPE zh_concat_im AUTHID CURRENT_USER AS OBJECT
(
CURR_STR clob,
STATIC FUNCTION ODCIAGGREGATEINITIALIZE(SCTX IN OUT zh_concat_im)
RETURN NUMBER,
MEMBER FUNCTION ODCIAGGREGATEITERATE(SELF IN OUT zh_concat_im,
P1 IN VARCHAR2) RETURN NUMBER,
MEMBER FUNCTION ODCIAGGREGATETERMINATE(SELF IN zh_concat_im,
RETURNVALUE OUT clob,
FLAGS IN NUMBER)
RETURN NUMBER,
MEMBER FUNCTION ODCIAGGREGATEMERGE(SELF IN OUT zh_concat_im,
SCTX2 IN zh_concat_im) RETURN NUMBER
);
--TYPE BODY
CREATE OR REPLACE TYPE BODY zh_concat_im IS
STATIC FUNCTION ODCIAGGREGATEINITIALIZE(SCTX IN OUT zh_concat_im)
RETURN NUMBER IS
BEGIN
SCTX := zh_concat_im(NULL);
RETURN ODCICONST.SUCCESS;
END;
MEMBER FUNCTION ODCIAGGREGATEITERATE(SELF IN OUT zh_concat_im,
P1 IN VARCHAR2) RETURN NUMBER IS
BEGIN
IF (CURR_STR IS NOT NULL) THEN
CURR_STR := CURR_STR || ',' || P1;
ELSE
CURR_STR := P1;
END IF;
RETURN ODCICONST.SUCCESS;
END;
MEMBER FUNCTION ODCIAGGREGATETERMINATE(SELF IN zh_concat_im,
RETURNVALUE OUT clob,
FLAGS IN NUMBER) RETURN NUMBER IS
BEGIN
RETURNVALUE := CURR_STR;
RETURN ODCICONST.SUCCESS;
END;
MEMBER FUNCTION ODCIAGGREGATEMERGE(SELF IN OUT zh_concat_im,
SCTX2 IN zh_concat_im) RETURN NUMBER IS
BEGIN
IF (SCTX2.CURR_STR IS NOT NULL) THEN
SELF.CURR_STR := SELF.CURR_STR || ',' || SCTX2.CURR_STR;
END IF;
RETURN ODCICONST.SUCCESS;
END;
END;
--FUNCTION
create or replace FUNCTION zh_concat(P1 VARCHAR2) RETURN clob AGGREGATE USING zh_concat_im;