Mysql/Mariadb查询在查询数据时动态地将行转换为列

Question

我查看了Mysql query to dynamically convert rows to columns的答案，但由于我需要连接表以获取所有信息，所以我无法使其工作。你能帮我把'问题'作为列名吗？

datestamp   pay  benefits ... career advancement 
--------------------------------------------------------------------- 
2/16/2017 11:55  Somewhat Slightyly  Slightly 
2/16/2017 11:55  Agree  Somewhat  Very 

的数据是这样的：

id datestamp  survey_col   value 
----------------------------------------------- 
1 2/16/2017 11:55 885457X234X1368SQ001 A3 
1 2/16/2017 11:55 885457X234X1368SQ002 A4 
1 2/16/2017 11:55 885457X234X1368SQ003 A4 
1 2/16/2017 11:55 885457X234X1368SQ004 A3 
1 2/16/2017 11:55 885457X234X1368SQ005 A2 
1 2/16/2017 11:55 885457X234X1368SQ006 A3 
1 2/16/2017 11:55 885457X234X1368SQ007 A4 
1 2/16/2017 11:55 885457X234X1368SQ008 A3 
1 2/16/2017 11:55 885457X234X1368SQ009 A4 
1 2/16/2017 11:55 885457X234X1368SQ010 A1 

我使用这个代码：

SELECT T.id, T.datestamp, SQ.question, 
     IF(type IN ("K", "N", "S", "T", "Y", "*") AND type NOT IN ("F"), 
     T.value, 
     IF(parent_qid = 0, SA.answer, SA2.answer) 
    ) as answer 
     FROM survey_questions SQ 
     JOIN survey_lookup SL ON SL.qid = SQ.qid 
     JOIN tmp T ON T.survey_col = SL.survey_col 
     LEFT JOIN survey_answers SA ON SA.qid = SQ.qid 
     AND SA.code = T.value 
     AND SA.language = 'en' 
     LEFT JOIN survey_answers SA2 on SA2.qid = SQ.parent_qid 
     AND SA2.code = T.value 
     AND SA2.language = 'en' 
     WHERE SQ.language = 'en' 
     ; 

其中规定：

id datestamp  question       answer 
---------------------------------------------------------------- 
1 2/16/2017 11:55 Pay         Somewhat 
1 2/16/2017 11:55 Benefits (health plan, leave, etc.) Slightly 
1 2/16/2017 11:55 Career Advancement     Slightly 
1 2/16/2017 11:55 Access to Training     Somewhat 
1 2/16/2017 11:55 Leadership Style     Very 
1 2/16/2017 11:55 Manager/Supervisor Style   Somewhat 
1 2/16/2017 11:55 Please enter comments    The company's policies... 

此代码工作时，所有的数据在一张桌子上，我不需要你se加入。

SET @sql = NULL; 
    SET SESSION GROUP_CONCAT_MAX_LEN = 1000000; -- default is 1024 
    SELECT 
     GROUP_CONCAT(DISTINCT 
     CONCAT(
      'MAX(IF(question = ''', REPLACE(question,"'", "\\'"), ''', answer, NULL)) AS ''', REPLACE(question,"'", "\\'"), '''' 
     ) 
    ) INTO @sql 
     FROM tmp; 

     SET @sql = CONCAT('SELECT row_id, submitdate, ', @sql, ' FROM ', survey_report, ' GROUP BY row_id'); 

     IF DEBUG = 1 THEN 
     SELECT @sql; 
     END IF; 

     PREPARE stmt FROM @sql; 
     EXECUTE stmt; 
     DEALLOCATE PREPARE stmt; 

这是一个没有REPLACE功能的尝试（我想使用它）。

SELECT 
    GROUP_CONCAT(DISTINCT 
    CONCAT(
    'MAX(IF(SQ.question = ', '''SQ.question''',' 
     IF(type IN ("K", "N", "S", "T", "Y", "*") AND type NOT IN ("F"), 
     T.value, 
     IF(parent_qid = 0, SA.answer, SA2.answer) 
    ) as answer, NULL)) as answer', '''SQ.question''') 
) INTO @sql 
    FROM survey_questions SQ 
    JOIN survey_lookup SL ON SL.qid = SQ.qid 
    JOIN tmp T ON T.survey_col = SL.survey_col 
    LEFT JOIN survey_answers SA ON SA.qid = SQ.qid 
    AND SA.code = T.value 
    AND SA.language = 'en' 
    LEFT JOIN survey_answers SA2 on SA2.qid = SQ.parent_qid 
    AND SA2.code = T.value 
    AND SA2.language = 'en' 
    WHERE SQ.language = 'en'; 

    SET @sql = CONCAT('SELECT id, datestamp, ', @sql, ' FROM tmp GROUP BY id'); 

    SELECT @sql; 

    PREPARE stmt FROM @sql; 
    EXECUTE stmt; 
    DEALLOCATE PREPARE stmt; 

Answer 1

这工作，但我不想创建另一个表。

DROP TEMPORARY TABLE IF EXISTS `tmp2`; 
CREATE TEMPORARY TABLE tmp2 
    SELECT T.id, T.datestamp, SQ.question, 
     IF(type IN ("K", "N", "S", "T", "Y", "*") AND type NOT IN ("F"), 
     T.value, 
     IF(parent_qid = 0, SA.answer, SA2.answer) 
    ) as answer 
     FROM survey_questions SQ 
     JOIN survey_lookup SL ON SL.qid = SQ.qid 
     JOIN tmp T ON T.survey_col = SL.survey_col 
     LEFT JOIN survey_answers SA ON SA.qid = SQ.qid 
     AND SA.code = T.value 
     AND SA.language = 'en' 
     LEFT JOIN survey_answers SA2 on SA2.qid = SQ.parent_qid 
     AND SA2.code = T.value 
     AND SA2.language = 'en' 
     WHERE SQ.language = 'en' 
     ; 

- select * from tmp2;

  SET @sql = NULL; 
    SET SESSION GROUP_CONCAT_MAX_LEN = 1000000; -- default is 1024 
    SELECT 
     GROUP_CONCAT(DISTINCT 
     CONCAT(
      'MAX(IF(question = ''', REPLACE(question,"'", "\\'"), ''', answer, NULL)) AS ''', REPLACE(question,"'", "\\'"), '''' 
     ) 
    ) INTO @sql 
     FROM tmp2; 
     SET @sql = CONCAT('SELECT id, datestamp, ', @sql, ' FROM tmp2 GROUP BY id'); 

     SELECT @sql; 

     PREPARE stmt FROM @sql; 
     EXECUTE stmt; 
     DEALLOCATE PREPARE stmt;