GROUP BY two different columns

Question

I store hits. My table looks like this:

    ID |   time   |   Country   
--------------------------------
    1  | 01:00:00 |    France
    2  | 01:00:00 |    France
    3  | 01:00:00 |    Brazil
    4  | 01:00:00 |    USA
    5  | 02:00:00 |    USA

This is my query:

SELECT COUNT(*) as total_hits, HOUR(time) as hour, Country
FROM hits 
WHERE time >= CURDATE() 
GROUP BY HOUR(time)

It does count how many hits I got and groups it by hours:

    time   |   total_hits   
---------------------------
  01:00:00 |    4
  02:00:00 |    1

I want one result grouped by time column and another grouped by countries column. This is what I need:

1) Grouped by hours like this (same like above)

    time   |   total_hits   
---------------------------
  01:00:00 |    4
  02:00:00 |    1

2) AND grouped by countries like this

  country  |   total_hits   
---------------------------
 France    |    2
  USA      |    2
 Brazil    |    1

I could do:

SELECT
       COUNT(*)
     , HOUR(time)
     , COUNT(IF( Country = 'France', Country, null)) AS France
     , COUNT(IF( Country = 'USA', Country, null)) AS USA
     , COUNT(IF( Country = 'Brazil', Country, null)) AS Brazil
FROM hits
WHERE time >= CURDATE()
GROUP BY HOUR(time)

Or alternatively with CASE or SUM(Country = 'France') AS France.

But in the country column there are more than just 3 countries. If I would do this with every country my query would be very long.

I could do this:

SELECT COUNT(*), Country, HOUR(time)
FROM hits 
WHERE time >= CURDATE() 
GROUP BY Country, HOUR(time)

But the ouput will be something like this:

  time     | country   |   total_hits   
---------------------------------------
  01:00:00 |  France   |    2
  01:00:00 |  USA      |    1
  01:00:00 |  Brazil   |    1
  02:00:00 |  USA      |    1

However I need an output like mentioned above.

So basically I need these queries in one query:

1) Group by HOUR (same like mentioned above)

SELECT COUNT(*) as total_hits, HOUR(time) as hour, Country
FROM hits 
WHERE time >= CURDATE() 
GROUP BY HOUR(time)

2) AND Group by Country

SELECT COUNT(*) as total_hits
FROM hits 
WHERE time >= CURDATE() 
GROUP BY Country

Performance is important. The database has millions of entries. Maybe MySQL is not the best way for this problem?

I find the way you are displaying this output to be confusing. Can you put it in a column sort of output method? — Zane, Jun 19, 2014 at 20:40
I did edit my question. Hope it's a little bit less confusing. — yoshi, Jun 19, 2014 at 21:03

RolandoMySQLDBA · Accepted Answer · 2014-06-21 23:07:35Z

I don't think I can help you with the formatting, but the query you need is this one:

PROPOSED QUERY

SELECT
    IFNULL(Hour,CONCAT('Total for ',IFNULL(Country,'All Countries'))) Statistic,
    COUNT(1) TotalHits
FROM
(
    SELECT Country,(time - INTERVAL MOD(UNIX_TIMESTAMP(time),3600) SECOND) Hour
    FROM hits WHERE time >= (DATE(NOW()) + INTERVAL 0 SECOND)
) AA
GROUP BY Country,Hour WITH ROLLUP;

YOUR SAMPLE DATA

USE test
DROP TABLE IF EXISTS hits;
CREATE TABLE hits
(
    id int not null auto_increment,
    time datetime,
    country varchar(20),
    PRIMARY KEY (id)
);
INSERT INTO hits (time,Country) VALUES
('2014-06-19 01:00:00','France'),
('2014-06-19 01:00:00','Brazil'),
('2014-06-19 01:00:00','USA'),
('2014-06-19 02:00:00','USA');

YOUR SAMPLE DATA LOADED

mysql> USE test
Database changed
mysql> DROP TABLE IF EXISTS hits;
Query OK, 0 rows affected (0.01 sec)

mysql> CREATE TABLE hits
    -> (
    ->     id int not null auto_increment,
    ->     time datetime,
    ->     country varchar(20),
    ->     PRIMARY KEY (id)
    -> );
Query OK, 0 rows affected (0.01 sec)

mysql> INSERT INTO hits (time,Country) VALUES
    -> ('2014-06-19 01:00:00','France'),
    -> ('2014-06-19 01:00:00','Brazil'),
    -> ('2014-06-19 01:00:00','USA'),
    -> ('2014-06-19 02:00:00','USA');
Query OK, 4 rows affected (0.00 sec)
Records: 4  Duplicates: 0  Warnings: 0

mysql> SELECT * FROM hits;
+----+---------------------+---------+
| id | time                | country |
+----+---------------------+---------+
|  1 | 2014-06-19 01:00:00 | France  |
|  2 | 2014-06-19 01:00:00 | Brazil  |
|  3 | 2014-06-19 01:00:00 | USA     |
|  4 | 2014-06-19 02:00:00 | USA     |
+----+---------------------+---------+
4 rows in set (0.00 sec)

mysql>

PROPOSED QUERY EXECUTED

mysql> SELECT
    ->     IFNULL(Hour,CONCAT('Total for ',IFNULL(Country,'All Countries'))) Statistic,
    ->     COUNT(1) TotalHits
    -> FROM
    -> (
    ->     SELECT Country,(time - INTERVAL MOD(UNIX_TIMESTAMP(time),3600) SECOND) Hour
    ->     FROM hits WHERE time >= (DATE(NOW()) + INTERVAL 0 SECOND)
    -> ) AA
    -> GROUP BY Country,Hour WITH ROLLUP;
+-------------------------+-----------+
| Statistic               | TotalHits |
+-------------------------+-----------+
| 2014-06-19 01:00:00     |         1 |
| Total for Brazil        |         1 |
| 2014-06-19 01:00:00     |         1 |
| Total for France        |         1 |
| 2014-06-19 01:00:00     |         1 |
| 2014-06-19 02:00:00     |         1 |
| Total for USA           |         2 |
| Total for All Countries |         4 |
+-------------------------+-----------+
8 rows in set (0.00 sec)

mysql>

I'll leave the formatting to you :-)

CAVEAT: Please make sure you have a time index on the table

ALTER TABLE hits ADD INDEX time_index (time);

An additional query could be

SELECT
    IFNULL(Country,CONCAT('Total for ',IFNULL(Hour,DATE(NOW())))) Statistic,
    COUNT(1) TotalHits
FROM
(
    SELECT Country,(time - INTERVAL MOD(UNIX_TIMESTAMP(time),3600) SECOND) Hour
    FROM hits WHERE time >= (DATE(NOW()) + INTERVAL 0 SECOND)
) AA
GROUP BY Hour,Country WITH ROLLUP;

whose output would be

+-------------------------------+-----------+
| Statistic                     | TotalHits |
+-------------------------------+-----------+
| Brazil                        |         1 |
| France                        |         1 |
| USA                           |         1 |
| Total for 2014-06-19 01:00:00 |         3 |
| USA                           |         1 |
| Total for 2014-06-19 02:00:00 |         1 |
| Total for 2014-06-19          |         4 |
+-------------------------------+-----------+
7 rows in set (0.00 sec)

UPDATE 2014-06-21 19:07 EDT

Perhaps the the two queries combined with UNION will work for you

SELECT
    IFNULL(Country,CONCAT('Total for ',IFNULL(Hour,DATE(NOW())))) Statistic,
    COUNT(1) TotalHits
FROM
(
    SELECT Country,(time - INTERVAL MOD(UNIX_TIMESTAMP(time),3600) SECOND) Hour
    FROM hits WHERE time >= (DATE(NOW()) + INTERVAL 0 SECOND)
) AA
GROUP BY Hour,Country
UNION
SELECT
    IFNULL(Hour,CONCAT('Total for ',IFNULL(Country,'All Countries'))) Statistic,
    COUNT(1) TotalHits
FROM
(
    SELECT Country,(time - INTERVAL MOD(UNIX_TIMESTAMP(time),3600) SECOND) Hour
    FROM hits WHERE time >= (DATE(NOW()) + INTERVAL 0 SECOND)
) AA
GROUP BY Country,Hour WITH ROLLUP;

I removed the WITH ROLLUP from the first one so that the total comes out once

First of all, Thank you very much! Incredible, really! You offered 2 queries. But both are only "50%" of what I want. The first query gives total for countries. The other gives total for dates. But I need both. I hope I am clear. — yoshi, Jun 19, 2014 at 21:20

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GROUP BY two different columns

1 Answer 1

PROPOSED QUERY

YOUR SAMPLE DATA

YOUR SAMPLE DATA LOADED

PROPOSED QUERY EXECUTED

I'll leave the formatting to you :-)

UPDATE 2014-06-21 19:07 EDT

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GROUP BY two different columns

1 Answer 1

PROPOSED QUERY

YOUR SAMPLE DATA

YOUR SAMPLE DATA LOADED

PROPOSED QUERY EXECUTED

I'll leave the formatting to you :-)

UPDATE 2014-06-21 19:07 EDT

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