Multi dynamic rows into multi column MySQL - mysql

Question

I'm using MySQL. I have to separate multi repeated rows into columns. The table has following structure.
But I need like this.
Note: There will be always 6 records of each DateTime. But Title and Feedback are dynamic. I tried to use
select DateTime,
But this is not giving my expected value. I wrote a code (not considered about title):
select
g.dateTime AS dateTime,
g.feedback as feedback ,
c.title AS title
from gauge g
inner join category c on g.category_id=c.category_id AND c.title ='title' AND g.feedback ='feedback'
group by g.dateTime
This doesn't work and I tried GROUP_CONCAT(.... SEPARATOR'.....' ) this gives me not expected output, just gives output in one column. My approach might be wrong.

Answer 1

Use a dynamic pivot since there are many different values
Fiddle to play with
drop table t;
create table t
(
dateTime datetime,
title varchar(50),
feedback int
);
insert into t values
( '2018-06-29 12:55:36', 'A', 1),
( '2018-06-29 12:55:36', 'B', 2),
( '2018-06-22 12:55:36', 'A', 1),
( '2018-06-22 12:55:36', 'B', 2),
( '2018-06-22 12:55:36', 'C', 3);
SET #sql = NULL;
SELECT
GROUP_CONCAT(DISTINCT
CONCAT(
'MAX(CASE WHEN title = ''',
title,
''' THEN ''', title ,''' END) AS ',
CONCAT(' Title',title,',')
),
CONCAT(
'MAX(CASE WHEN feedback = ''',
feedback,
''' THEN ''', feedback ,''' END) AS ',
CONCAT(' Feedback',feedback)
)
) INTO #sql
FROM T;
SET #sql = CONCAT('SELECT dateTime, ', #sql, '
FROM t
GROUP BY dateTime');
PREPARE stmt FROM #sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

Answer 2

I would simply use conditional aggregation. Enumerating the values is a bit tricky in MySQL (unless you are using MySQL 8+):
select datetime,
max(case when rn = 1 then title end) as title_1,
max(case when rn = 1 then feedback end) as feedback_1,
max(case when rn = 2 then title end) as title_2,
max(case when rn = 2 then feedback end) as feedback_2,
max(case when rn = 3 then title end) as title_3,
max(case when rn = 3 then feedback end) as feedback_3,
max(case when rn = 4 then title end) as title_4,
max(case when rn = 4 then feedback end) as feedback_4,
max(case when rn = 5 then title end) as title_5,
max(case when rn = 5 then feedback end) as feedback_5,
max(case when rn = 6 then title end) as title_6,
max(case when rn = 6 then feedback end) as feedback_6
from (select gc.*,
(#rn := if(#dt = g.dateTime, #rn + 1,
if(#dt := g.dateTime, 1, 1)
)
) as rn
from (select g.dateTime, g.feedback, c.title AS title
from gauge g inner join
category c
on g.category_id = c.category_id and
c.title = 'title' and
g.feedback = 'feedback'
group by g.dateTime
order by g.dateTime
) gc cross join
(select #dt := '', #rn := 0) params
) gc
group by datetime;
I don't think the filtering on c.title and g.feedback is correct.

Answer 3

Not an optimized approach but you may join them into table and filter according to row number modulo by 6. This way, we can separate the 6 rows into 6 different table
http://rextester.com/DLVV64095
SELECT MAIN.DateTime,
TBL1.TITLE AS Title1,
TBL1.FEEDBACK AS Feedback1,
TBL2.TITLE AS Title2,
TBL2.FEEDBACK AS Feedback2,
TBL3.TITLE AS Title3,
TBL3.FEEDBACK AS Feedback3,
TBL4.TITLE AS Title4,
TBL4.FEEDBACK AS Feedback4,
TBL5.TITLE AS Title5,
TBL5.FEEDBACK AS Feedback5,
TBL6.TITLE AS Title6,
TBL6.FEEDBACK AS Feedback6
FROM (
SELECT [DATETIME] AS [DateTime]
FROM GAUGE
GROUP BY [DATETIME]
) MAIN
INNER JOIN (
SELECT G.DATETIME,
G.FEEDBACK,
C.TITLE,
ROW_NUMBER() OVER(PARTITION BY ORDER BY (SELECT 1) ASC) AS ROWNO
FROM GAUGE G
INNER JOIN CATEGORY C
ON G.CATEGORY_ID = C.CATEGORY_ID
) TBL1
ON TBL1.DATETIME = MAIN.[DateTime]
AND TBL1.ROWNO % 6 = 1
INNER JOIN (
SELECT G.DATETIME,
G.FEEDBACK,
C.TITLE,
ROW_NUMBER() OVER(PARTITION BY ORDER BY (SELECT 1) ASC) AS ROWNO
FROM GAUGE G
INNER JOIN CATEGORY C
ON G.CATEGORY_ID = C.CATEGORY_ID
) TBL2
ON TBL2.DATETIME = MAIN.[DateTime]
AND TBL2.ROWNO % 6 = 2
INNER JOIN (
SELECT G.DATETIME,
G.FEEDBACK,
C.TITLE,
ROW_NUMBER() OVER(PARTITION BY ORDER BY (SELECT 1) ASC) AS ROWNO
FROM GAUGE G
INNER JOIN CATEGORY C
ON G.CATEGORY_ID = C.CATEGORY_ID
) TBL3
ON TBL3.DATETIME = MAIN.[DateTime]
AND TBL3.ROWNO % 6 = 3
INNER JOIN (
SELECT G.DATETIME,
G.FEEDBACK,
C.TITLE,
ROW_NUMBER() OVER(PARTITION BY ORDER BY (SELECT 1) ASC) AS ROWNO
FROM GAUGE G
INNER JOIN CATEGORY C
ON G.CATEGORY_ID = C.CATEGORY_ID
) TBL4
ON TBL4.DATETIME = MAIN.[DateTime]
AND TBL4.ROWNO % 6 = 4
INNER JOIN (
SELECT G.DATETIME,
G.FEEDBACK,
C.TITLE,
ROW_NUMBER() OVER(PARTITION BY ORDER BY (SELECT 1) ASC) AS ROWNO
FROM GAUGE G
INNER JOIN CATEGORY C
ON G.CATEGORY_ID = C.CATEGORY_ID
) TBL5
ON TBL5.DATETIME = MAIN.[DateTime]
AND TBL5.ROWNO % 6 = 5
INNER JOIN (
SELECT G.DATETIME,
G.FEEDBACK,
C.TITLE,
ROW_NUMBER() OVER(PARTITION BY ORDER BY (SELECT 1) ASC) AS ROWNO
FROM GAUGE G
INNER JOIN CATEGORY C
ON G.CATEGORY_ID = C.CATEGORY_ID
) TBL6
ON TBL6.DATETIME = MAIN.[DateTime]
AND TBL6.ROWNO % 6 = 0