在Linux中，如果想将一个字符串，例如“aaa,bbb,ccc,ddd”以逗号拆分，得到其中的某个值如“ccc”，可以使用如下命令：echo "aaa,bbb,ccc,ddd" | awk -F, '{print $3}'，这样的功能在SQL中也同样可以实现，参考以下表函数：

CREATE FUNCTION fawk(
    func_serch char(1),
    func_chars varchar(2048)
)
RETURNS table(
    id integer,
    values varchar(128)
)
SPECIFIC fawk
LANGUAGE SQL
CONTAINS SQL
RETURN
  WITH temp(pvalue, plocate, nplocate) as(
  SELECT substr(func_chars, 1, nplocate -1),
         nplocate,
         nplocate
    FROM TABLE(VALUES (locate(func_serch, func_chars))) t(nplocate)
   WHERE nplocate > 0
 
  UNION ALL
 
  SELECT (case when nplocate > 1 then substr(pvalue, 1, nplocate - 1) else substr(pvalue, 1) end),
         plocate + nplocate,
         nplocate
    FROM (
          SELECT pvalue,
                 plocate,
                 nplocate pplocate,
                 locate(func_serch, pvalue) nplocate
            FROM (
                  SELECT (CASE WHEN plocate + 1 <= length(func_chars) THEN substr(func_chars, plocate + 1) ELSE '' END) pvalue,
                         plocate,
                         nplocate
                    FROM temp
                 ) t
         ) t
   WHERE nplocate > 0 OR (nplocate = 0 AND pplocate <> 0)
  ) SELECT rownumber() over() id,
           pvalue
      FROM temp
      ORDER BY plocate
@

执行查询：select values from table(fawk(',', 'aaa,bbb,ccc,ddd')) t where id = 3