Row to column transformation in MySQL version 8.0.17 using Pivot

Question

Unfortunately MySQL does not have a PIVOT function which is basically for what I trying to do.

I need on the return set rows values as column name using the stored procedure below this link

I populate a table of a database MySql version 8.0.17, with an external file in csv format.

This is the table filled with data from the external csv file

+-----------------------+--------+-----+
| contents              | sUnity | sID |
+-----------------------+--------+-----+
| Set n.1               | Q400   |   4 |
| - Par 1.1             | Q400   |   6 |
| <b>bold text</b>      | Q400   |   7 |
| - Par 1.2             | Q400   |   9 |
| normal text           | Q400   |  10 |
| Set n.2               | Q400   |  12 |
| - Par 2.1             | Q400   |  14 |
| <i>italic text</i>    | Q400   |  15 |
| - Par 2.2             | Q400   |  16 |
| <u>underline text</u> | Q400   |  17 |
| - Par 2.3             | Q400   |  71 |
| Set n.1               | Q410   |  72 |
| - Par 1.1             | Q410   |  73 |
| <b>bold text</b>      | Q410   |  74 |
| - Par 1.2             | Q410   |  75 |
| normal text           | Q410   |  76 |
| Set n.2               | Q410   |  77 |
| - Par 2.1             | Q410   |  78 |
| <i>italic text</i>    | Q410   |  79 |
| - Par 2.2             | Q410   |  80 |
| <u>underline text</u> | Q410   |  81 |
| - Par 2.3             | Q410   |  82 |
+-----------------------+--------+-----+
22 rows in set (0.03 sec)

Now I need this return I mean set rows values as column name

+-----------------------+-----------------------+
| Q400                  | Q410                  |
+-----------------------+-----------------------+
| Set n.1               | Set n.1               |
| - Par 1.1             | - Par 1.1             |
| <b>bold text</b>      | <b>bold text</b>      |
| - Par 1.2             | - Par 1.2             |
| normal text           | normal text           |
| Set n.2               | Set n.2               |
| - Par 2.1             | - Par 2.1             |
| <i>italic text</i>    | <i>italic text</i>    |
| - Par 2.2             | - Par 2.2             | 
| <u>underline text</u> | <u>underline text</u> |
| - Par 2.3             | - Par 2.3             | 
| Set n.1               | Set n.1               |
| - Par 1.1             | - Par 1.1             |
| <b>bold text</b>      | <b>bold text</b>      |
| - Par 1.2             | - Par 1.2             |
| normal text           | normal text           |
| Set n.2               | Set n.2               |
| - Par 2.1             | - Par 2.1             |
| <i>italic text</i>    | <i>italic text</i>    | 
| - Par 2.2             | - Par 2.2             | 
| <u>underline text</u> | <u>underline text</u> |
| - Par 2.3             | - Par 2.3             |
+-----------------------+-----------------------+

Stored procedure and return ( I'm sorry but if I adding the SP code this question is not released... )

+-----+-------------+-------------+--------+
| sID | sUnity_Q400 | sUnity_Q410 | sUnity |
+-----+-------------+-------------+--------+
|   6 | Q400        | NULL        | Q400   |
|  73 | NULL        | Q410        | Q410   |
|   9 | Q400        | NULL        | Q400   |
|  75 | NULL        | Q410        | Q410   |
|  14 | Q400        | NULL        | Q400   |
|  78 | NULL        | Q410        | Q410   |
|  16 | Q400        | NULL        | Q400   |
|  80 | NULL        | Q410        | Q410   |
|  71 | Q400        | NULL        | Q400   |
|  82 | NULL        | Q410        | Q410   |
|   7 | Q400        | NULL        | Q400   |
|  74 | NULL        | Q410        | Q410   |
|  15 | Q400        | NULL        | Q400   |
|  79 | NULL        | Q410        | Q410   |
|  17 | Q400        | NULL        | Q400   |
|  81 | NULL        | Q410        | Q410   |
|  10 | Q400        | NULL        | Q400   |
|  76 | NULL        | Q410        | Q410   |
|   4 | Q400        | NULL        | Q400   |
|  72 | NULL        | Q410        | Q410   |
|  12 | Q400        | NULL        | Q400   |
|  77 | NULL        | Q410        | Q410   |
+-----+-------------+-------------+--------+
22 rows in set (0.05 sec)

Structure and data of table below

-- ----------------------------
-- Table structure for t_contents_s3sv_1_2021
-- ----------------------------
DROP TABLE IF EXISTS `t_contents_s3sv_1_2021`;
CREATE TABLE `t_contents_s3sv_1_2021`  (
  `contents` varchar(255) DEFAULT NULL,
  `sUnity` varchar(50) DEFAULT NULL,
  `sID` int(11) NOT NULL AUTO_INCREMENT,
  PRIMARY KEY (`sID`) USING BTREE,
  UNIQUE INDEX `contents`(`contents`, `sUnity`) USING BTREE
) ENGINE = InnoDB;

-- ----------------------------
-- Records of t_contents_s3sv_1_2021
-- ----------------------------
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('- Par 1.1', 'Q400', 6);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('- Par 1.1', 'Q410', 73);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('- Par 1.2', 'Q400', 9);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('- Par 1.2', 'Q410', 75);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('- Par 2.1', 'Q400', 14);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('- Par 2.1', 'Q410', 78);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('- Par 2.2', 'Q400', 16);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('- Par 2.2', 'Q410', 80);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('- Par 2.3', 'Q400', 71);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('- Par 2.3', 'Q410', 82);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('<b>bold text</b>', 'Q400', 7);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('<b>bold text</b>', 'Q410', 74);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('<i>italic text</i>', 'Q400', 15);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('<i>italic text</i>', 'Q410', 79);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('<u>underline text</u>', 'Q400', 17);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('<u>underline text</u>', 'Q410', 81);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('normal text', 'Q400', 10);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('normal text', 'Q410', 76);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('Set n.1', 'Q400', 4);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('Set n.1', 'Q410', 72);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('Set n.2', 'Q400', 12);
INSERT INTO `t_contents_s3sv_1_2021` VALUES ('Set n.2', 'Q410', 77);

You do not have a column to group by on as grouping seems to be done on a row number based on ordering by sUnity and sID. Generate this group-wise ranking number and group by on that. See this answer to generate group-wise row numbers (rankings): https://stackoverflow.com/a/52393883/5389997 — Shadow, Mar 05 '21 at 10:55

JamieD77 · Accepted Answer · 2021-03-05T15:43:03.110

you should be able to pivot if you replace [sID] with a rownumber that will link the [sUnity] values by order of their ID's

select      max(IF(sUnity = 'Q400', t.contents, NULL))    [Q400]
            , max(IF(sUnity = 'Q410', t.contents, NULL))  [Q410]
from        (   select  row_number() over (partition by sUnity order by sID) as rn
                        , tcs.sUnity
                        , tcs.contents
                from    dbo.t_contents_s3sv_1_2021 as tcs) as t
group by    rn
order by    rn

if row_number is not available you can use this to mimic row_number

SET @row_number := 0;
SELECT MAX(IF(sUnity = 'Q400', contents, NULL)) Q400,
       MAX(IF(sUnity = 'Q410', contents, NULL)) Q410
FROM(
SELECT 
    @row_number:=CASE
        WHEN @sUnity = sUnity 
          THEN 
              @row_number + 1
          ELSE 
               1
        END AS num,
    @sUnity:=sUnity sUnity,
    contents
FROM
    t_contents_s3sv_1_2021
ORDER BY 
    sUnity, sID
  ) t
GROUP BY num;

Row to column transformation in MySQL version 8.0.17 using Pivot

1 Answers1

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