SQL Regex - 替换为另一个字段的子字符串

Question

我有一个数据库表(Oracle 11g)的问卷反馈,包括多项选择,多个答案问题.Options列具有用户可以选择的每个值,Answers列具有他们选择的数值.

ID_NO     OPTIONS                               ANSWERS
1001      Apple Pie|Banana-Split|Cream Tea      1|2
1002      Apple Pie|Banana-Split|Cream Tea      2|3
1003      Apple Pie|Banana-Split|Cream Tea      1|2|3

我需要一个能够解码答案的查询,并将答案的文本版本作为单个字符串.

ID_NO     ANSWERS     ANSWER_DECODE
1001      1|2         Apple Pie|Banana-Split
1002      2|3         Banana-Split|Cream Tea
1003      1|2|3       Apple Pie|Banana-Split|Cream Tea

我已经尝试使用正则表达式来替换值并获得子串,但我无法找到一种方法来正确合并这两者.

WITH feedback AS (
  SELECT 1001 id_no, 'Apple Pie|Banana-Split|Cream Tea' options, '1|2' answers FROM DUAL UNION
  SELECT 1002 id_no, 'Apple Pie|Banana-Split|Cream Tea' options, '2|3' answers FROM DUAL UNION
  SELECT 1003 id_no, 'Apple Pie|Banana-Split|Cream Tea' options, '1|2|3' answers FROM DUAL )
SELECT 
  id_no,
  options,
  REGEXP_SUBSTR(options||'|', '(.)+?\|', 1, 2) second_option,
  answers,
  REGEXP_REPLACE(answers, '(\d)+', ' \1 ') answer_numbers,
  REGEXP_REPLACE(answers, '(\d)+', REGEXP_SUBSTR(options||'|', '(.)+?\|', 1, To_Number('2'))) "???"
FROM feedback

我不想手动定义或解码SQL中的答案; 有很多调查都有不同的问题(以及不同数量的选项),所以我希望有一个解决方案可以动态地为所有问题工作.

我试图通过LEVEL将选项和答案拆分成单独的行,并在代码匹配的地方重新加入它们,但实际数据集运行得非常慢(带有600行响应的5选项问题).

WITH feedback AS (
  SELECT 1001 id_no, 'Apple Pie|Banana-Split|Cream Tea' options, '1|2' answers FROM DUAL UNION
  SELECT 1002 id_no, 'Apple Pie|Banana-Split|Cream Tea' options, '2|3' answers FROM DUAL UNION
  SELECT 1003 id_no, 'Apple Pie|Banana-Split|Cream Tea' options, '1|2|3' answers FROM DUAL )
SELECT
    answer_rows.id_no,
    ListAgg(option_rows.answer) WITHIN GROUP(ORDER BY option_rows.lvl)
FROM
  (SELECT DISTINCT
    LEVEL lvl,
    REGEXP_SUBSTR(options||'|', '(.)+?\|', 1, LEVEL) answer
  FROM
    (SELECT DISTINCT
      options,
      REGEXP_COUNT(options||'|', '(.)+?\|') num_choices
    FROM
      feedback)
  CONNECT BY LEVEL <= num_choices
  ) option_rows
  LEFT OUTER JOIN
  (SELECT DISTINCT
    id_no,
    to_number(REGEXP_SUBSTR(answers, '(\d)+', 1, LEVEL)) answer
  FROM
    (SELECT DISTINCT
      id_no,
      answers,
      To_Number(REGEXP_SUBSTR(answers, '(\d)+$')) max_answer
    FROM
      feedback)
  WHERE
    to_number(REGEXP_SUBSTR(answers, '(\d)+', 1, LEVEL)) IS NOT NULL
  CONNECT BY LEVEL <= max_answer
  ) answer_rows
    ON option_rows.lvl = answer_rows.answer
GROUP BY
    answer_rows.id_no
ORDER BY
  answer_rows.id_no

如果没有使用正则表达式的解决方案,是否有比LEVEL更有效的方法来分割值？或者还有另一种方法可行吗？

Answer 1

它很慢，因为你将每一行展开太多次；您使用的 connect-by 子句正在查找所有行，因此您最终会得到大量数据然后进行排序 - 这可能就是您最终在DISTINCT那里得到的原因。

您可以PRIOR向连接方式添加两个子句，首先是为了ID_NO保留，第二个是为了避免循环 - 任何非确定性函数都可以做到这一点，我已经选择了，dbms_random.value但如果您愿意，也可以使用sys_guid，或者其他。你也不需要很多子查询，你可以用两个来完成；或者作为 CTE，我认为它更清楚一些：

WITH feedback AS (
  SELECT 1001 id_no, 'Apple Pie|Banana-Split|Cream Tea' options, '1|2' answers FROM DUAL UNION
  SELECT 1002 id_no, 'Apple Pie|Banana-Split|Cream Tea' options, '2|3' answers FROM DUAL UNION
  SELECT 1003 id_no, 'Apple Pie|Banana-Split|Cream Tea' options, '1|2|3' answers FROM DUAL
),
option_rows AS (
  SELECT
    id_no,
    LEVEL answer,
    REGEXP_SUBSTR(options, '[^|]+', 1, LEVEL) answer_text
  FROM feedback
  CONNECT BY LEVEL <= REGEXP_COUNT(options, '[^|]+')
  AND id_no = PRIOR id_no
  AND PRIOR dbms_random.value IS NOT NULL
),
answer_rows AS (
  SELECT
    id_no,
    REGEXP_SUBSTR(answers, '[^|]+', 1, LEVEL) answer
  FROM feedback
  CONNECT BY LEVEL <= REGEXP_COUNT(answers, '[^|]+')
  AND PRIOR id_no = id_no
  AND PRIOR dbms_random.value IS NOT NULL
)
SELECT
  option_rows.id_no,
  LISTAGG(option_rows.answer, '|') WITHIN GROUP (ORDER BY option_rows.answer) AS answers,
  LISTAGG(option_rows.answer_text, '|') WITHIN GROUP (ORDER BY option_rows.answer) AS answer_decode
FROM option_rows
JOIN answer_rows
ON option_rows.id_no = answer_rows.id_no
AND option_rows.answer = answer_rows.answer
GROUP BY option_rows.id_no
ORDER BY option_rows.id_no;

得到：

     ID_NO ANSWERS    ANSWER_DECODE                          
---------- ---------- ----------------------------------------
      1001 1|2        Apple Pie|Banana-Split                  
      1002 2|3        Banana-Split|Cream Tea                  
      1003 1|2|3      Apple Pie|Banana-Split|Cream Tea  

我还更改了您的正则表达式模式，因此您不必附加或删除|.