按范围分组24小时时间

Question

I have a number of rows that are in 24 hour format like this

What i would like is to have a format like this one

+------+------+----------+
| from | to   | count(*) |
+------+------+----------+
| 0000 |  0100|        3 |
| 0100 | 0200 |        4 |
|  0200| 0300 |        2 |
| 0300 | 0400 |        1 |
+------+------+----------+

I have tried this

SELECT COUNT(*) `count`,
       100*FLOOR(the_amount/100) `from`,
       100*FLOOR(the_amount/100)+99 `to`
  FROM r_data
 where transaction_type = 'send'
 GROUP BY FLOOR(the_amount/100) ORDER BY COUNT(*) DESC

but this gives only one row.How should i write a query to group my time that is in 24 hour format?.

Answer 1

Try this:

SELECT
  LPAD(100*FLOOR(24_hour_time/100),4,0) AS `from`,
  LPAD(100*FLOOR(24_hour_time/100) + 100,4,0) AS `to`,
  COUNT(*) AS `count`
FROM
  r_data
WHERE
  transaction_typ = 'send'
GROUP BY 1
ORDER BY 24_hour_time;

But it will only show you "populated hours".