Can I concatenate multiple MySQL rows Group into one field?

Question

Using MySQL, I can do something like:

SELECT sum(capacity) FROM table_name GROUP BY HOUR(time) ;

My Output:

but instead I just want 1 row, 1 col:

Expected Output:

1240, 987, 1092, 1205

Research [GROUP_CONCAT](https://dev.mysql.com/doc/refman/8.0/en/group-by-functions.html#function_group-concat) , pretty sure that is what you are asking here.. — Raymond Nijland, Aug 02 '19 at 13:01
Your question is a duplicate of [this](https://stackoverflow.com/questions/276927/can-i-concatenate-multiple-mysql-rows-into-one-field) one. — Angel Politis, Aug 02 '19 at 13:02
Consider handling issues of data display in application code - Note that in your example, you have no way of knowing which sum belongs to which hour. — Strawberry, Aug 02 '19 at 13:09
to add to @Strawberry 's comment also the results are most likely different between MySQL 5 and MySQL 8 as MySQL 8 has removed implict `GROUP BY` sorting as it was deprecated since MySQL 5.7.. Also meaning that this will result into non deterministic ("random") sorting results on MySQL 8 — Raymond Nijland, Aug 02 '19 at 13:16

score 0 · Answer 1 · edited Aug 02 '19 at 13:20

0

You could use group concat on your result

  SELECT group_concat(my_sum)
  from  (
    select  sum(capacity) my_sum
    FROM table_name 
    GROUP BY HOUR(time) 
    ORDER BY Hour(time)
  ) t

edited Aug 02 '19 at 13:20

Raymond Nijland

answered Aug 02 '19 at 13:02

ScaisEdge

Note: MySQL 8 has removed implict `GROUP BY` sorting as it was deprecated since MySQL 5.7.. Also meaning that this will result into non deterministic ("random") sorting results on MySQL 8.. So this might need to have a `ORDER BY` – Raymond Nijland Aug 02 '19 at 13:18
Well `ORDER BY Hour(time)` can still cause non deterministic ("random") sorting results if the values "ties" forgot to mention... You will need to add atleast one deterministic column to the `ORDER BY`, meaning the column must have a primary or unique key to get pure 100% deterministic (fixed) result on every run. – Raymond Nijland Aug 02 '19 at 13:23

1 Answers1