如何在MySQL中拆分逗号分隔的记录字符串并按顺序排列？

我想创建一个MySQL查询，从下表中分别选择记录

   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

期待回答

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

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如果您的值在tblA中，并且希望插入到tblB中，那么可以像这样进行查询

insert into tblB (date) select date from tblA;

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您可以使用MySQL子字符串索引。它将在指定的分隔符出现次数之前，从给定的逗号分隔字符串返回子字符串

试试这个，似乎效果不错：

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。。

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为了进一步研究，请告诉我们这是因为您已经意识到原始设计中存在一个根本性缺陷，现在想纠正它！

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;