在 MySQL 中以特定方式数据透视表

Question

还有其他数据透视表问题，但我似乎找不到我的问题的答案。

这是我的桌子

ID    QUESTION       ANSWER       RECORDID      SORTORDER
1     Question 1     Answer 1.1   123456        1
2     Question 2     Answer 2.1   123456        2
3     Question 3     Answer 3.1   123456        3
4     Question 1     Answer 1.2   654321        1
5     Question 2     Answer 2.2   654321        2
6     Question 3     Answer 3.2   654321        3

等等

我想通过查询将其输出到：

Question 1    Question 2    Question 3
Answer 1.1    Answer 2.1    Answer 3.1
Answer 1.2    Answer 2.2    Answer 3.2

简而言之，问题列包含不唯一的问题（在此演示中有 2 个条目（请参阅 RECORDID）），因此需要按排序顺序对它们进行分组和排序。 RECORDID 始终是唯一的

我看到了一些枢轴/非枢轴示例，但无法理解它。 有人可以帮我解决这个问题吗？

Answer 1

这应该可以解决问题。在内部查询中，您只能获得特定问题的答案，而在外部查询中，当您按 recordid 分组时，您会摆脱空值...尝试仅运行内部查询以了解想法。

select  
  max(q.Question1),
  max(q.Question2),
  max(q.Question3) FROM (SELECT     
                         recordid,
                         case when question = 'Question 1' then answer else null end as Question1, 
                         case when question = 'Question 2' then answer else null end as Question2, 
                         case when question = 'Question 3' then answer else null end as Question3 FROM questions) q group by q.recordid

如果您有任何问题，请告诉我！

编辑：您的评论增加了另一个级别的复杂性:) 现在我知道我们如何使用该排序顺序列...我们需要一个内部查询来获取问题及其排序顺序。然后按每个排序顺序获取答案，然后按记录 id 分组以过滤掉空值并获得所需的结果。请试试这个，让我知道它是怎么回事... select 语句中的问题数必须等于问题最多的表单中的问题数 - 我输入 8 只是为了向您展示这不应该限制你。现在您将不依赖于问题名称 - 只依赖于排序编号。最好有排序顺序 - 否则您必须为每个记录 ID 生成一个行号...

SET @rank=0; SET @id:=0; select recordid, max(qq.question1) as 'Question 1', max(qq.question2) as 'Question 2', max(qq.question3) as 'Question 3', max(qq.question4) as 'Question 4', max(qq.question5) as 'Question 5', max(qq.question6) as 'Question 6', max(qq.question7) as 'Question 7', max(qq.question8) as 'Question 8' FROM ( SELECT recordid, case when q.rownumber = 1 then CONCAT(question,': ', answer) else null end as question1, case when q.rownumber = 2 then CONCAT(question,': ', answer) else null end as question2, case when q.rownumber = 3 then CONCAT(question,': ', answer) else null end as question3, case when q.rownumber = 4 then CONCAT(question,': ', answer) else null end as question4, case when q.rownumber = 5 then CONCAT(question,': ', answer) else null end as question5, case when q.rownumber = 6 then CONCAT(question,': ', answer) else null end as question6, case when q.rownumber = 7 then CONCAT(question,': ', answer) else null end as question7, case when q.rownumber = 8 then CONCAT(question,': ', answer) else null end as question8 FROM( select recordid, question, answer, sortorder, @rank:=CASE WHEN @id=recordid THEN @rank+1 ELSE 1 END as rownumber, @id:=recordid from questions order by recordid, sortorder ) q )qq GROUP BY recordid

Answer 2

谢谢大家（尤其是 Koshera！），经过一些调整，我让它按我想要的方式工作。

这是总代码（原始，概念证明；））。 函数 processQuery 是一个带有参数化查询的 try / catch PDO 执行（参见 ? 占位符，“原始” $i 应该没有问题吗？）。

<div class="database-container">
<table border="0" cellspacing="0" cellpadding="7">
<tr>

<?php

// get all questions and group them so we only get unique questions
$getQuestions = processQuery("SELECT ansr_question FROM forms_123456 WHERE is_answer=1 and ansr_type != 'text' GROUP BY ansr_question ORDER BY ansr_sortorder ASC",$param,'fetch-raw',$server,$extra,$DBH);
unset($param);

// fetch all the questions
while($fetchQuestions = $getQuestions->fetch())

    {

        // save into array and generate the column questions
        $questions[] = $fetchQuestions["ansr_question"];
        $question_headers .= '<td height="19" nowrap style="background-color:#e9e9e9; font-weight:400;">'.trim(ucfirst($fetchQuestions["ansr_question"])).'</td>';

    }

// loop array
$num_questions = count($questions);
$num_questions_check = $num_questions -1;
for($i=0; $num_questions > $i; ++$i)

    {

    // prepare PDO params
    $param[] = $questions[$i];

    // use the count to perform if statement when last question has been reached
    $comma = ',';
    if($num_questions_check == $i)

        {
        $comma = '';
        }

    // generate the 2 dynamic parts of the query
    $sql_part1 .= "max(qq.question$i) as 'answer$i',";
    $sql_part2 .= "case when q.ansr_question = ? then ansr_answer else null end as question$i$comma ";

    }


// make it 1 query
$query = "select 
$sql_part1
ansr_recordid, 
ansr_type
FROM (
    SELECT
        ansr_recordid, 
        ansr_type,
        $sql_part2
    FROM(
        select 
            ansr_recordid, 
            ansr_question,
            ansr_answer,
            ansr_type,
            ansr_sortorder
            from forms_123456 where is_answer=1 order by ansr_recordid, ansr_sortorder 
            ) q
    )qq
GROUP BY ansr_recordid";

// lets try it!
$getAnswers = processQuery($query,$param,'fetch-raw',$server,$extra,$DBH);
unset($param);


// show questions and other data
echo '<td height="19" nowrap style="background-color:#e9e9e9; font-weight:600;">Status</td>
    <td height="19" nowrap style="background-color:#e9e9e9; font-weight:600;">Details</td>';

echo $question_headers;

echo '<td height="19" nowrap style="background-color:#e9e9e9; font-weight:600;">Record ID</td>
    <td height="19" nowrap style="background-color:#e9e9e9; font-weight:600;">Start Date</td>
    <td height="19" nowrap style="background-color:#e9e9e9; font-weight:600;">End Date</td>
</tr>';


// show values ----------------------------------------
$first = 1;
while($fetch = $getAnswers->fetch())

{

// change color per row
if($first == 0)

    {
    $first = 1;
    $bgcolor = '#f1f1f1';
    }
else
    {
    $first = 0;
    $bgcolor = '';
    }

echo '<tr>';

echo '<td height="19" nowrap style="background-color:'.$bgcolor.'; font-weight:400;">OK</td>
    <td height="19" nowrap style="background-color:'.$bgcolor.'; font-weight:400;">Bekijken</td>';

// loop the number of questions so we get the same amount of columns
for($i=0; $num_questions > $i; ++$i)

    {
    echo '<td height="19" nowrap style="background-color:'.$bgcolor.'; font-weight:400;">'.trim(ucfirst($fetch["answer$i"])).'</td>';
    }

echo '<td height="19" nowrap style="background-color:'.$bgcolor.'; font-weight:400;">'.$fetch["ansr_recordid"].'</td>
    <td height="19" nowrap style="background-color:'.$bgcolor.'; font-weight:400;">Start Date</td>
    <td height="19" nowrap style="background-color:'.$bgcolor.'; font-weight:400;">End Date</td>';

echo '</tr>';

}

?>

</table>
</div>