mysql 计算多路复用条目的多次出现

Question

我有一个 mysql 表，如下所示，

  id          reasonCode
------      ------------------
  1           0, 1
  2           0
  3           1, 2, 3
  4           2
  5           1, 0

我想要输出为

  reasonCode           occurrences

    0                      3
    1                      3
    2                      2
    3                      1

我尝试了“group by”，但它给出了类似这样的东西。

  reasonCode           occurrences

    0, 1                   1
    0                      1
    1, 2, 3                1
    2                      1
    1, 0                   1

如果有人知道如何做到这一点，我们将不胜感激。

Answer 1

尝试这个查询

SELECT Reason,COUNT(Reason) FROM
(
SELECT
  id,
  SUBSTRING_INDEX(SUBSTRING_INDEX(reasoncode, ',', n.digit+1), ',', -1) Reason
FROM
  table1
  INNER JOIN
  (SELECT 0 digit UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3) n
  ON LENGTH(REPLACE(reasoncode, ',' , '')) <= LENGTH(reasoncode)-n.digit
ORDER BY
  id,
  n.digit
) T

Group By Reason;

<强> SQL FIDDLE

输出将是:

REASON  OCCURANCES
0           3
1           3
2           2
3           1