我从通用问题/答案数据中获取姓名和地址数据，以创建某种规范化的报告数据库。

我得到的查询使用 group_concat，适用于单组问题，但不适用于多组问题。

我试图通过仅使用名字和姓氏以及 3 条记录来简化我正在做的事情，其中​​ 2 条用于 1 个人，1 条用于另一个人。实际上虽然有超过 300,000 条记录。

Example qs.Id = 1 的结果。

QuestionSetId       Forename        Surname
-------------------------------------------------------
            1       Bob             Jones

Example qs.Id IN (1, 2, 3) 的结果。

QuestionSetId       Forename        Surname
-------------------------------------------------------
            3       Bob,Bob,Frank   Jones,Jones,Smith

对于 qs.Id IN (1, 2, 3)，我希望看到什么。

QuestionSetId       Forename        Surname
-------------------------------------------------------
            1       Bob             Jones
            2       Bob             Jones
            3       Frank           Smith

那么如何让第二个示例为每组名称和地址信息返回一个单独的行？

我意识到当前数据存储方式“有问题”，但我无法更改数据存储方式。

我可以得到 sets of individual answers但不确定如何组合其他的。

我无法更改的简化架构:

CREATE TABLE StaticQuestion (
  Id INT NOT NULL,
  StaticText VARCHAR(500) NOT NULL);

CREATE TABLE Question (
  Id INT NOT NULL, 
  Text VARCHAR(500) NOT NULL);

CREATE TABLE StaticQuestionQuestionLink (
  Id INT NOT NULL,
  StaticQuestionId INT NOT NULL,
  QuestionId INT NOT NULL,
  DateEffective DATETIME NOT NULL);

CREATE TABLE Answer (
  Id INT NOT NULL,
  Text VARCHAR(500) NOT NULL);

CREATE TABLE QuestionSet (
  Id INT NOT NULL,
  DateEffective DATETIME NOT NULL);

CREATE TABLE QuestionAnswerLink (
  Id INT NOT NULL,
  QuestionSetId INT NOT NULL,
  QuestionId INT NOT NULL,
  AnswerId INT NOT NULL,
  StaticQuestionId INT NOT NULL);

一些仅包含名字和姓氏的示例数据。

INSERT INTO StaticQuestion (Id, StaticText)
VALUES (1, 'FirstName'),
       (2, 'LastName');

INSERT INTO Question (Id, Text)
VALUES (1, 'What is your first name?'),
       (2, 'What is your forename?'),
       (3, 'What is your Surname?');

INSERT INTO StaticQuestionQuestionLink (Id, StaticQuestionId, QuestionId, DateEffective)
VALUES (1, 1, 1, '2001-01-01'),
       (2, 1, 2, '2008-08-08'),
       (3, 2, 3, '2001-01-01');

INSERT INTO Answer (Id, Text)
VALUES (1, 'Bob'),
       (2, 'Jones'),
       (3, 'Bob'),
       (4, 'Jones'),
       (5, 'Frank'),
       (6, 'Smith');

INSERT INTO QuestionSet (Id, DateEffective)
VALUES (1, '2002-03-25'),
       (2, '2009-05-05'),
       (3, '2009-08-06');

INSERT INTO QuestionAnswerLink (Id, QuestionSetId, QuestionId, AnswerId, StaticQuestionId)
VALUES (1, 1, 1, 1, 1),
       (2, 1, 3, 2, 2),
       (3, 2, 2, 3, 1),
       (4, 2, 3, 4, 2),
       (5, 3, 2, 5, 1),
       (6, 3, 3, 6, 2);

以防万一 SQLFiddle 在下面是我链接到的示例中的 3 个查询:

1: - 工作查询但仅针对一组数据。

SELECT MAX(QuestionSetId) AS QuestionSetId,
       GROUP_CONCAT(Forename) AS Forename,
       GROUP_CONCAT(Surname) AS Surname
FROM   (SELECT
            x.QuestionSetId,
            CASE x.StaticQuestionId WHEN 1 THEN Text END AS Forename,
            CASE x.StaticQuestionId WHEN 2 THEN Text END AS Surname        
        FROM     (SELECT (SELECT   link.StaticQuestionId
                          FROM     StaticQuestionQuestionLink link
                          WHERE    link.Id = qa.QuestionId
                               AND link.DateEffective <= qs.DateEffective
                               AND link.StaticQuestionId IN (1, 2)
                          ORDER BY link.DateEffective DESC LIMIT 1) AS StaticQuestionId,
                         a.Text,
                         qa.QuestionSetId
                  FROM   QuestionSet qs
                            INNER JOIN QuestionAnswerLink qa ON qs.Id = qa.QuestionSetId
                            INNER JOIN Answer a ON qa.AnswerId = a.Id
                  WHERE  qs.Id IN (1)) x) y

2: - 工作查询但在多组数据上出现不希望的结果。

SELECT MAX(QuestionSetId) AS QuestionSetId,
       GROUP_CONCAT(Forename) AS Forename,
       GROUP_CONCAT(Surname) AS Surname
FROM   (SELECT
            x.QuestionSetId,
            CASE x.StaticQuestionId WHEN 1 THEN Text END AS Forename,
            CASE x.StaticQuestionId WHEN 2 THEN Text END AS Surname        
        FROM     (SELECT (SELECT   link.StaticQuestionId
                          FROM     StaticQuestionQuestionLink link
                          WHERE    link.Id = qa.QuestionId
                               AND link.DateEffective <= qs.DateEffective
                               AND link.StaticQuestionId IN (1, 2)
                          ORDER BY link.DateEffective DESC LIMIT 1) AS StaticQuestionId,
                         a.Text,
                         qa.QuestionSetId
                  FROM   QuestionSet qs
                            INNER JOIN QuestionAnswerLink qa ON qs.Id = qa.QuestionSetId
                            INNER JOIN Answer a ON qa.AnswerId = a.Id
                  WHERE  qs.Id IN (1, 2, 3)) x) y

3: - 虽然仅在 1 个字段(答案)上对多组数据进行工作查询。

SELECT
    qs.Id AS QuestionSet,
    a.Text AS Answer
FROM
    QuestionSet qs
        INNER JOIN QuestionAnswerLink qalink ON qs.Id = qalink.QuestionSetId
        INNER JOIN StaticQuestionQuestionLink sqqlink ON qalink.QuestionId = sqqlink.QuestionId
        INNER JOIN Answer a ON qalink.AnswerId = a.Id
WHERE
        sqqlink.StaticQuestionId = 1 /* FirstName */
    AND sqqlink.DateEffective = 
            (SELECT DateEffective
               FROM StaticQuestionQuestionLink
              WHERE StaticQuestionId = 1 
                AND DateEffective <= qs.DateEffective
           ORDER BY DateEffective
               DESC 
              LIMIT 1)

最佳答案

@PeteGo，试试这个

SELECT
    qs.Id AS QuestionSet,
    GROUP_CONCAT(a.Text SEPARATOR ', ')  AS Answer
FROM
    QuestionSet qs
        INNER JOIN QuestionAnswerLink qalink ON qs.Id = qalink.QuestionSetId
        INNER JOIN StaticQuestionQuestionLink sqqlink ON qalink.QuestionId = sqqlink.QuestionId
        INNER JOIN Answer a ON qalink.AnswerId = a.Id
WHERE
        sqqlink.StaticQuestionId in (1,2,3) /* FirstName */
GROUP BY qs.Id;

或

SELECT
    qs.Id AS QuestionSet,
    group_CONCAT(b.Text ORDER BY b.Id )   AS Answer
FROM
    QuestionSet qs
        INNER JOIN QuestionAnswerLink qalink ON qs.Id = qalink.QuestionSetId
        INNER JOIN StaticQuestionQuestionLink sqqlink ON qalink.QuestionId = sqqlink.QuestionId
        INNER JOIN Answer a ON qalink.AnswerId = a.Id
INNER JOIN Answer b ON qalink.AnswerId = b.Id
WHERE
        sqqlink.StaticQuestionId in (1,2,3)  
   group by qs.Id  ;

或

select qs.Id, group_concat(a.Text order by a.Id) from QuestionAnswerLink qalink
left join QuestionSet qs on qalink.QuestionSetId=qs.Id
left join Answer a on qalink.AnswerId = a.Id


 left join QuestionSet qs1 on qalink.QuestionSetId=qs1.Id
left join Answer b on qalink.AnswerId = b.Id


group by qs.Id ;

关于MySQL 查询 GROUP_CONCAT 多行，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/13753739/