change multi rows to one row-multi column - mysql

Question

For some reason i have to do this. i have a query that have result like this :
limit usage tariff total
0 10 10 700 7000
11 20 10 900 9000
21 30 10 1800 18000
31 > 11 2700 29700
the query return 4 rows maximum (like above) or sometime just 3 rows.
I want to change the rows to just one row and multi column like this (the list below just one row):
limit1 usage1 tariff1 total1 limit2 usage2 tariff2 total2
0 10 10 700 7000 11 20 10 900 9000
limit3 usage3 tariff3 total3 limit4 usage4 tariff4 total4
21 30 10 1800 18000 31 > 11 2700 29700
if the query return just 3 rows, the values in column limit4 until total4 will be empty. I dont know how to do like that.
EDITED
I add one ID column so the list will be :
ID limit usage tariff total
1 0 10 10 700 7000
2 11 20 10 900 9000
3 21 30 10 1800 18000
4 31 > 11 2700 29700
I try to make it one row like this :
SELECT e.*,f.id AS id4,f.limit AS limit4,f.usage AS usage4,f.tariff AS tariff4,f.total AS total4
FROM
(SELECT c.*,d.id AS id3,d.limit AS limit3,d.usage AS usage3,d.tariff AS tariff3,d.total AS total3
FROM
(SELECT b.id AS id1,b.limit AS limit1,b.usage AS usage1,b.tariff AS tariff1,b.total AS total1,
a.id AS id2,a.limit AS limit2,a.usage AS usage2,a.tariff AS tariff2,a.total AS total2
FROM testtariff a
INNER JOIN testtariff b ON a.id!=b.id
LIMIT 1) c INNER JOIN testtariff d ON c.id1 != d.id AND c.id2 != d.id
LIMIT 1) e INNER JOIN testtariff f ON e.id1 != f.id AND e.id2 != f.id
AND e.id3 != f.id
LIMIT 1
it work as i expected for 4 rows but not work for 3 rows. should i use cursor ?

Answer 1

This is generally called a "pivot". Here's how you do it:
select
'0 10' as limit1,
sum(limit between 0 and 10 * usage) as usage1,
sum(limit between 0 and 10 * tariff) as tariff1,
sum(limit between 0 and 10 * usage * tariff) as total1,
'11 20' as limit2,
sum(limit between 11 and 20 * usage) as usage2,
sum(limit between 11 and 20 * tariff) as tariff2,
sum(limit between 11 and 20 * usage * tariff) as total2,
-- etc
from mytable
group by 1,5 -- etc
This works because limit between x and x is 1 if true and 0 if false, so using multiplying by this is a simple way to filter the results into different groups.