Splits函数(截取函数)

拆分函数
CREATE OR REPLACE FUNCTION splitstr (str   IN CLOB,
                                                 i     IN NUMBER := 0,
                                                 sep   IN VARCHAR2 := ',')
   RETURN VARCHAR2
/**************************************
  * Function: 返回字符串被指定字符分割后的指定节点字符串。
  * Parameters: str: 待分割的字符串。
  i: 返回第几个节点。当i为0返回str中的所有字符，当i 超过可被分割的个数时返回空。
  sep: 分隔符，默认逗号，也可以指定字符或字符串。当指定的分隔符不存在于str中时返回sep中的字符。
  * Example: select splitstr('abc,def', 1) as str from dual; 得到 abc
  select splitstr('abc,def', 3) as str from dual; 得到 空
  **************************************/
IS
   t_i       NUMBER;
   t_count   NUMBER;
   t_str     VARCHAR2 (4000);
BEGIN
   IF i = 0
   THEN
      t_str := str;
   ELSIF INSTR (str, sep) = 0
   THEN
      t_str := sep;
   ELSE
      SELECT COUNT (*) INTO t_count FROM TABLE (split (str, sep));

      IF i <= t_count
      THEN
         SELECT str
           INTO t_str
           FROM (SELECT ROWNUM AS item, COLUMN_VALUE AS str
                   FROM TABLE (split (str, sep)))
          WHERE item = i;
      END IF;
   END IF;

   RETURN t_str;
END;

CREATE OR REPLACE TYPE type_split IS TABLE OF VARCHAR2 (4000) 

CREATE OR REPLACE FUNCTION split (p_list VARCHAR2, p_sep VARCHAR2 := ',')
   RETURN type_split
   
   PIPELINED
IS
   l_idx    PLS_INTEGER;
   v_list   VARCHAR2 (4000) := p_list;
BEGIN
   LOOP
      l_idx := INSTR (v_list, p_sep);

      IF l_idx > 0
      THEN
         PIPE ROW (SUBSTR (v_list, 1, l_idx - 1));
         v_list := SUBSTR (v_list, l_idx + LENGTH (p_sep));
      ELSE
         PIPE ROW (v_list);
         EXIT;
      END IF;
   END LOOP;
   RETURN;
END split;