Oracle: Create WM_CONCAT function for version 12c +

CREATE OR REPLACE TYPE wm_concat_impl AUTHID CURRENT_USER AS OBJECT ( curr_str VARCHAR2 (32767), STATIC FUNCTION odciaggregateinitialize (sctx IN OUT wm_concat_impl) RETURN NUMBER, MEMBER FUNCTION odciaggregateiterate ( SELF IN OUT wm_concat_impl, p1 IN VARCHAR2 ) RETURN NUMBER, MEMBER FUNCTION odciaggregateterminate ( SELF IN wm_concat_impl, returnvalue OUT VARCHAR2, flags IN NUMBER ) RETURN NUMBER, MEMBER FUNCTION odciaggregatemerge ( SELF IN OUT wm_concat_impl, sctx2 IN wm_concat_impl ) RETURN NUMBER ); CREATE OR REPLACE TYPE BODY wm_concat_impl IS STATIC FUNCTION odciaggregateinitialize (sctx IN OUT wm_concat_impl) RETURN NUMBER IS BEGIN sctx := wm_concat_impl (NULL); RETURN odciconst.success; END; MEMBER FUNCTION odciaggregateiterate ( SELF IN OUT wm_concat_impl, 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 wm_concat_impl, returnvalue OUT VARCHAR2, flags IN NUMBER ) RETURN NUMBER IS BEGIN returnvalue := curr_str; RETURN odciconst.success; END; MEMBER FUNCTION odciaggregatemerge ( SELF IN OUT wm_concat_impl, sctx2 IN wm_concat_impl ) 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; CREATE OR REPLACE FUNCTION wm_concat (p1 VARCHAR2) RETURN VARCHAR2 AGGREGATE USING wm_concat_impl;