Oracle 行拼接 wmsys.wm_concat扩展

将多行数据拼接成一行：

--wmsys.wm_concat
select wmsys.wm_concat(a.hdid) as test from flow_currentrecord a where a.flowid=222 group by a.flowid;

但有大小限制：字符串缓冲区太小，超过varchar 4000长度。
扩展：更改返回类型为clob

--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;

调用：

select zh_concat(a.hdid) as test from flow_currentrecord a where a.flowid=222 group by a.flowid;