oracle把一个字段按逗号拆开

Question

将一个字段值如22,37,42,84,40按逗号拆开单个分解输出，字段内数值可能会有长度变化如122,137,142,184,140，请问如何解决？

Answer 1

用正则截取加递归

SELECT REGEXP_SUBSTR(T.STR, '[^,]+', 1, LEVEL) AS A
  FROM (select '22,37,42,84,40' str from dual) T
CONNECT BY LEVEL <= REGEXP_COUNT(T.STR, '[^,]+')

另外一种截取方式和另外一种递归方式

with t as
 (select '22,37,42,84,40' || ',' str from dual),
x(val,lvl) as
 (select substr(str, 1, instr(str, ',') - 1), 1 lvl
    from t
  union all
  select substr(str,
                instr(str, ',', 1, lvl) + 1,
                instr(str, ',', 1, lvl + 1) - instr(str, ',', 1, lvl) - 1),
         lvl + 1
    from x, t
   where instr(str, ',', 1, lvl + 1) <> 0)
select * from x;