MySQL / Mariadb 存储过程、Prepared Statement、Union、来自动态创建的表和列名的值

Question

我想创建报告，而不必在 Excel 中为每个报告创建数据透视表。

我有一个调查软件，可以为每个调查创建一个新表格。列以 ID 号命名。所以，我永远不知道这些列将被命名。该软件根据问题的“类型”将答案存储在两个不同的表格中。 （文本、单选按钮等）

我手动创建了一个表“survey_answers_lookup”，其中存储了一些关键字段，但它重复了答案。程序“survey_report”运行良好，可以生成所需的数据，但存在挑战。

由于调查表是在有人创建新调查时创建的，因此我需要在架构上创建一个触发器来创建第二个触发器，我认为这是不可能的。第二个触发器将监控调查表，并在有人完成调查后将数据插入到“survey_answers_lookup”表中。

我可以编辑 php 软件并将值插入到survey_answers_lookup 表中，但是当我更新软件时会产生更多的工作。 （我必须更新文件，然后将我的更改放回文件中）。我也无法确定他们将值插入表格的位置。

你能帮忙吗？

已编辑。我在下面发布了我的解决方案。

Answer 1

将 some_user 更改为有权访问数据库的用户。

CREATE DEFINER=`some_user`@`localhost` PROCEDURE `usp_produce_survey_report`(IN survey_id VARCHAR(10), IN lang VARCHAR(2))
    SQL SECURITY INVOKER
BEGIN

/*---------------------------------------------------------------------------------
I do not guarantee that this will work for you or that it cannot be hacked with
with SQL injections or other malicious intents. 

This stored procedure will produce output that you may use to create a report.
It accepts two arguments; The survey id (745) and the language (en).
It parses the column name in the survey table to get the qid.

It will copy the answers from the survey table to the survey_report
table if the answer is type S or K. It will get the answers from
the answers table for other types. NOTE: Other types might need to
be added to the if statement.

Additionally, the qid and id from the survey table are also copied to
the survey_report table.

Then the questions from the questions table, and answers from the answers
and survey_report tables are combined and displayed.  

The data in the survey_report table is deleted after the data is displayed.

The id from the survey table is displayed as the respondent_id which may
be used to combine the questions and answers from a specific respondent.  

You may have to change the prefix on the table names.
Example: survey_answers to my_prefix_answers.

Use this to call the procedure.
Syntax:  call survey.usp_produce_survey_report('<SURVERY_ID>', '<LANGUAGE>');
Example: call survey.usp_produce_survey_report('457345', 'en'); 

use this to create the table that stores the data
 CREATE TABLE `survey_report` (
    `id` int(11) NOT NULL AUTO_INCREMENT,
    `qid` int(11) NOT NULL DEFAULT '0',
    `survey_row_id` int(11) NOT NULL DEFAULT '0' COMMENT 'id that is in the survey_<id> table',
    `answer` mediumtext COLLATE utf8mb4_unicode_ci DEFAULT NULL,
   PRIMARY KEY (`id`)
);
*/

DECLARE v_col_name VARCHAR (25);
DECLARE v_qid INT;
DECLARE v_col_count INT DEFAULT 0;
DECLARE done INT DEFAULT false;
DECLARE tname VARCHAR(24) DEFAULT CONCAT('survey_survey_',survey_id);
DECLARE counter INT DEFAULT 0;
DECLARE current_row INT DEFAULT 0;
DECLARE total_rows INT DEFAULT 0;

-- select locate ('X','123457X212X1125', 8);  -- use locate to determine location of second X - returns 11
-- select substring('123457X212X1125', 11+1, 7); -- use substring to get the qid - returns 1125

DECLARE cur1 cursor for
    SELECT column_name, substring(column_name, 11+1, 7) as qid -- get the qid from the column name.  the 7 might need to be higher depending on the id.  
       FROM information_schema.columns -- this has the column names
       WHERE table_name = tname -- table name created form the id that was passed to the stored procedure
       AND column_name REGEXP 'X'; -- get the columns that have an X

DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
SET done = FALSE;

OPEN cur1;

   SET total_rows = (SELECT table_rows -- get the number of rows
      FROM INFORMATION_SCHEMA.TABLES
      WHERE table_name = tname);
   -- SELECT total_rows;

   read_loop: LOOP
      FETCH cur1 INTO v_col_name, v_qid; -- v_col_name is the original column name and v_qid is the qid that is taken from the column name

      IF done THEN
         LEAVE read_loop;
      END IF;
      -- SELECT v_col_name, v_qid;   
      SET counter = 1; -- use to compare id's
      SET current_row = 1; -- used for the while loop

      WHILE current_row <= total_rows DO
         SET @sql := NULL;
         -- SELECT v_col_name, v_qid, counter, x; 
         -- SELECT counter as id, v_col_name, v_qid as qid, x;    
         -- SET @sql = CONCAT ('SELECT id ', ',',v_qid, ' as qid ,', v_col_name,' FROM ', tname, ' WHERE id = ', counter );
         -- I would have to join the survey table below if I did not add the answer (v_col_name). I assume this is faster than another join.
         SET @sql = CONCAT ('INSERT INTO survey_report(qid,survey_row_id,answer) SELECT ',v_qid, ',id,' , v_col_name, '  FROM ', tname, ' WHERE id = ', counter );

         -- SELECT @sql;       
         PREPARE stmt FROM @sql;
         EXECUTE stmt;
         DEALLOCATE PREPARE stmt;
         -- SELECT counter, x; 
         SET current_row = current_row + 1; -- increment counter for while loop
         SET counter = counter + 1; -- increment counter for id's
      END WHILE;
   END LOOP; -- read_loop
   CLOSE cur1;

   -- SELECT * FROM survey_report
   -- ORDER BY id, qid;

   SET @counter = 0;

   SELECT 
      @counter:=@counter + 1 AS newindex, -- increment the counter that is in the header
      survey_report.id,
      survey_report.survey_row_id as respondent_id, -- the id that copied from the survey table
      survey_report.qid,
      question,
      IF(type IN ('S' , 'K'),
         (SELECT answer
            FROM survey_report
            WHERE qid NOT IN (SELECT qid FROM survey_answers)
            AND survey_questions.language = lang
                  AND survey_report.id = @counter),
         (SELECT answer
            FROM survey_answers
            WHERE survey_questions.qid = survey_answers.qid
                  AND survey_report.qid = survey_questions.qid
                  AND survey_report.answer = survey_answers.code
                  AND survey_answers.language = lang
             )
          ) AS answer
       FROM survey_questions
          JOIN survey_report ON survey_report.qid = survey_questions.qid
          WHERE survey_questions.sid = survey_id
          ORDER BY survey_report.survey_row_id, survey_report.id;

   TRUNCATE TABLE survey_report;    
END