oracle 取俩个字符串的差集

思路：

--funcation RemoveSameStr(in_str,splitStr) ;用于去除重复值 ;
 SELECT  b.memberid,  RemoveSameStr(wm_concat(b.productidlist),',') AS productidlist
  FROM BASE_ACCOUNT_BILL_GROUP  b
  WHERE  b.grouptype =3
  GROUP BY  b.memberid ;

2.创建 FUNCTION REMOVESAMESTR(OLDSTR VARCHAR2, SIGN VARCHAR2);

CREATE OR REPLACE FUNCTION REMOVESAMESTR(OLDSTR VARCHAR2, SIGN VARCHAR2)
  RETURN VARCHAR2 IS
  STR          VARCHAR2(1000);
  CURRENTINDEX NUMBER;
  STARTINDEX   NUMBER;
  ENDINDEX     NUMBER;

  TYPE STR_TYPE IS TABLE OF VARCHAR2(30) INDEX BY BINARY_INTEGER;
  ARR STR_TYPE;

  RESULT VARCHAR2(1000);
BEGIN
  -- 空字符串
  IF OLDSTR IS NULL THEN
    RETURN('');
  END IF;
  --字符串太长
  IF LENGTH(OLDSTR) > 1000 THEN
    RETURN(OLDSTR);
  END IF;
  STR := OLDSTR;

  CURRENTINDEX := 0;
  STARTINDEX   := 0;

  LOOP
    CURRENTINDEX := CURRENTINDEX + 1;
    ENDINDEX     := INSTR(STR, SIGN, 1, CURRENTINDEX);
    IF (ENDINDEX <= 0) THEN
      EXIT;
    END IF;
  
    ARR(CURRENTINDEX) := TRIM(SUBSTR(STR,
                                     STARTINDEX + 1,
                                     ENDINDEX - STARTINDEX - 1));
    STARTINDEX := ENDINDEX;
  END LOOP;

  --取最后一个字符串:
  ARR(CURRENTINDEX) := SUBSTR(STR, STARTINDEX + 1, LENGTH(STR));

  --去掉重复出现的字符串:
  FOR I IN 1 .. CURRENTINDEX - 1 LOOP
    FOR J IN I + 1 .. CURRENTINDEX LOOP
      IF ARR(I) = ARR(J) THEN
        ARR(J) := '';
      END IF;
    END LOOP;
  END LOOP;

  STR := '';
  FOR I IN 1 .. CURRENTINDEX LOOP
    IF ARR(I) IS NOT NULL THEN
      STR := STR || SIGN || ARR(I);
      --数组置空:
      ARR(I) := '';
    END IF;
  END LOOP;
  --去掉前面的标识符:
  RESULT := SUBSTR(STR, 2, LENGTH(STR));
  RETURN(RESULT);
END REMOVESAMESTR;

3.创建 Function COMPARETWOSTR(IN_STR IN VARCHAR2) ；

CREATE OR REPLACE FUNCTION COMPARETWOSTR(IN_STR IN VARCHAR2)
  RETURN VARCHAR2 AS
  RESULTSTR VARCHAR2(4000);
BEGIN
  SELECT LISTAGG(STR, ',') WITHIN GROUP(ORDER BY STR)
    INTO RESULTSTR
    FROM (SELECT LEVEL STR
            FROM DUAL
          CONNECT BY LEVEL <= 17
          MINUS
          SELECT TO_NUMBER(COLUMN_VALUE) STR
            FROM TABLE(SPLITSTR(IN_STR, ',')));
  RETURN RESULTSTR;
EXCEPTION
  WHEN OTHERS THEN
    DBMS_OUTPUT.PUT_LINE(SQLCODE || SQLERRM ||
                         DBMS_UTILITY.FORMAT_ERROR_BACKTRACE);
END COMPARETWOSTR;

4.创建 function splitstr(p_string IN VARCHAR2, p_delimiter IN VARCHAR2) RETURN str_split ；

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

CREATE OR REPLACE FUNCTION splitstr(p_string IN VARCHAR2, p_delimiter IN VARCHAR2)
   /**********************************************************************
    * xdshi add blockment 2015-09-21
    * 通用方法：按列返回分割字符串后的内容
    * 入参：p_string 分割字符串
    *       p_delimiter 分割符
    * 返回：每个分割出来的字符串
    **********************************************************************/
    RETURN str_split
    PIPELINED
AS
    v_length   NUMBER := LENGTH(p_string);
    v_start    NUMBER := 1;
    v_index    NUMBER;
BEGIN
    WHILE(v_start <= v_length)
    LOOP
        v_index := INSTR(p_string, p_delimiter, v_start);

        IF v_index = 0
        THEN
            PIPE ROW(SUBSTR(p_string, v_start));
            v_start := v_length + 1;
        ELSE
            PIPE ROW(SUBSTR(p_string, v_start, v_index - v_start));
            v_start := v_index + 1;
        END IF;
    END LOOP;

    RETURN;
END splitstr;

 
 

5.最终结果