mysql - 如何在MySQL中分割逗号分隔的记录字符串并按顺序排列？

Question

我想要一个 MySQL 查询来分别从下表中选择记录

   ID  AgentID    Name   Return Date
   1   1,2,3       A     2016-05-22,2016-02-1,2016-1-15
   2   2,4         B     2016-03-22,2016-04-1

期待答案

ID  AgentID    Name   Return Date
1    1          A     2016-05-22
1    2          A     2016-02-1
1    3          A     2016-1-15
2    2          B     2016-03-22
2    4          B     2016-04-1

Answer 1

您可以使用 MySQL SUBSTRING_INDEX()。它将返回给定逗号分隔字符串中指定的分隔符出现次数之前的子字符串。

试试这个，看起来效果很好:

SELECT ID
       ,SUBSTRING_INDEX(SUBSTRING_INDEX(t.AgentID, ',', n.n), ',', -1) Agent
       ,Name
       ,SUBSTRING_INDEX(SUBSTRING_INDEX(t.Return_Date, ',', n.n), ',', -1) Return_Date
FROM table1 t CROSS JOIN 
 (
   SELECT a.N + b.N * 10 + 1 n
   FROM 
     (SELECT 0 AS N UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) a
    ,(SELECT 0 AS N UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) b
   ORDER BY n
  ) n

WHERE n.n <= 1 + (LENGTH(t.Return_Date) - LENGTH(REPLACE(t.Return_Date, ',', '')))
ORDER BY ID;

检查这个.. SQL Fiddle HERE

要进一步学习，请继续MySQL Split String Function