MySQL Query GROUP BY day / month / year

Question

Is it possible to make a simple query to count how many records I have in a determined period of time like a year, month, or day, having a TIMESTAMP field, like:

SELECT COUNT(id)
FROM stats
WHERE record_date.YEAR = 2009
GROUP BY record_date.YEAR

Or even:

SELECT COUNT(id)
FROM stats
GROUP BY record_date.YEAR, record_date.MONTH

To have a monthly statistic.

Thanks!

Answer 1

(Roughly) benchmarking some of the solutions on a 2.5M row table, it would appear that EXTRACT(YEAR_MONTH FROM date) is the clear performance winner currently.

GROUP BY DATE_FORMAT(`date`,'%Y-%m')
2.4555 seconds

GROUP BY EXTRACT(YEAR_MONTH FROM `date`)
1.3241 seconds

GROUP BY YEAR(date), MONTH(`date`)
1.8917 seconds

GROUP BY YEAR(date)*100 + MONTH(date)
1.7791 seconds

GROUP BY SUBSTRING(`date`,1,7)
2.2972 seconds

GROUP BY LEFT(`date`,7)
2.2346 seconds

It should be noted that none of these queries can make use of an index; therefore if you need better performance the simplest method is to add a VIRTUAL column (MySQL 5.7+) with an index:

ALTER TABLE `foobar`
ADD `date_year_month` MEDIUMINT UNSIGNED AS (EXTRACT(YEAR_MONTH FROM `date`)) VIRTUAL
AFTER `date`,
ADD INDEX (`date_year_month`);

GROUP BY `date_year_month`
0.0330 seconds

Answer 2

In simpler terms, without ONLY_FULL_GROUP_BY, you can write a query where you group data by one column but still display other columns in the result without needing to aggregate them. This can be more convenient for certain queries, but it's important to use this feature carefully to avoid unintended results. By default slq_mode is ONLY_FULL_GROUP_BY in mysql server, so just make sure whenever you group data you cannot show data which doesn't match with the group by. i.e if you are grouping by MONTH(TABLE.creation_date) THEN you cannot select TABLE.creation_date you have to convert it to SELECT MONTH(TABLE.creation_date)

Example:

// ❌ WRONG
SELECT DATE(TABLE.creation_date) FROM TABLE GROUP BY MONTH(inv.creation_date); // groups data by month
//END OF WRONG QUERY

// ✅ CORRECT
SELECT MONTH(TABLE.creation_date) FROM TABLE GROUP BY MONTH(inv.creation_date);
//END OF CORRECT QUERY

Answer 3

Or you can use group by clause like this,

//to get data by month and year do this ->
SELECT FORMAT(TIMESTAMP_COLUMN, 'MMMM yy') AS Month, COUNT(ID) FROM TABLE_NAME GROUP BY FORMAT(TIMESTAMP_COLUMN, 'MMMM yy')

if you want to fetch records by date then in group by change format to 'dd-mm-yy' or 'dd-MMMM-yyy'

Answer 4

try it

GROUP BY YEAR(record_date), MONTH(record_date)

Answer 5

I wanted to get similar data per day, after experimenting a bit, this is the fastest I could find for my scenario

SELECT COUNT(id)
FROM stats
GROUP BY record_date DIV 1000000;

If you want to have it per month, add additional zeroes (00) I would not recommend this from "make the code readable" perspective, it might also break in different versions. But in our case this took less then half the time compared to some other more clearer queries that I tested.

This is a MySQL answer (as MySQL is tagged in the question) and well documented in the manual https://dev.mysql.com/doc/refman/8.0/en/date-and-time-type-conversion.html

Answer 6

Here's one more approach. This uses [MySQL's LAST_DAY() function][1] to map each timestamp to its month. It also is capable of filtering by year with an efficient range-scan if there's an index on record_date.

  SELECT LAST_DAY(record_date) month_ending, COUNT(*) record_count
    FROM stats
   WHERE record_date >= '2000-01-01'
     AND record_date <  '2000-01-01' + INTERVAL 1 YEAR
   GROUP BY LAST_DAY(record_date) 

If you want your results by day, use DATE(record_date) instead.

If you want your results by calendar quarter, use YEAR(record_date), QUARTER(record_date).

Here's a writeup. https://www.plumislandmedia.net/mysql/sql-reporting-time-intervals/ [1]: https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_last-day

Answer 7

You can do this simply Mysql DATE_FORMAT() function in GROUP BY. You may want to add an extra column for added clarity in some cases such as where records span several years then same month occurs in different years.Here so many option you can customize this. Please read this befor starting. Hope it should be very helpful for you. Here is sample query for your understanding

SELECT
    COUNT(id),
    DATE_FORMAT(record_date, '%Y-%m-%d') AS DAY,
    DATE_FORMAT(record_date, '%Y-%m') AS MONTH,
    DATE_FORMAT(record_date, '%Y') AS YEAR

FROM
    stats
WHERE
    YEAR = 2009
GROUP BY
    DATE_FORMAT(record_date, '%Y-%m-%d ');

Answer 8

Complete and simple solution with similarly performing yet shorter and more flexible alternative currently active:

SELECT COUNT(*) FROM stats
-- GROUP BY YEAR(record_date), MONTH(record_date), DAYOFMONTH(record_date)
GROUP BY DATE_FORMAT(record_date, '%Y-%m-%d')

Answer 9

If your search is over several years, and you still want to group monthly, I suggest:

version #1:

SELECT SQL_NO_CACHE YEAR(record_date), MONTH(record_date), COUNT(*)
FROM stats
GROUP BY DATE_FORMAT(record_date, '%Y%m')

version #2 (more efficient):

SELECT SQL_NO_CACHE YEAR(record_date), MONTH(record_date), COUNT(*)
FROM stats
GROUP BY YEAR(record_date)*100 + MONTH(record_date)

I compared these versions on a big table with 1,357,918 rows (innodb), and the 2nd version appears to have better results.

version1 (average of 10 executes): 1.404 seconds
version2 (average of 10 executes): 0.780 seconds

(SQL_NO_CACHE key added to prevent MySQL from CACHING to queries.)

Answer 10

.... group by to_char(date, 'YYYY') --> 1989

.... group by to_char(date,'MM') -->05

.... group by to_char(date,'DD') --->23

.... group by to_char(date,'MON') --->MAY

.... group by to_char(date,'YY') --->89

Answer 11

I prefer to optimize the one year group selection like so:

SELECT COUNT(*)
  FROM stats
 WHERE record_date >= :year 
   AND record_date <  :year + INTERVAL 1 YEAR;

This way you can just bind the year in once, e.g. '2009', with a named parameter and don't need to worry about adding '-01-01' or passing in '2010' separately.

Also, as presumably we are just counting rows and id is never NULL, I prefer COUNT(*) to COUNT(id).

Answer 12

The following query worked for me in Oracle Database 12c Release 12.1.0.1.0

SELECT COUNT(*)
FROM stats
GROUP BY 
extract(MONTH FROM TIMESTAMP),
extract(MONTH FROM TIMESTAMP),
extract(YEAR  FROM TIMESTAMP);

Answer 13

If you want to filter records for a particular year (e.g. 2000) then optimize the WHERE clause like this:

SELECT MONTH(date_column), COUNT(*)
FROM date_table
WHERE date_column >= '2000-01-01' AND date_column < '2001-01-01'
GROUP BY MONTH(date_column)
-- average 0.016 sec.

Instead of:

WHERE YEAR(date_column) = 2000
-- average 0.132 sec.

The results were generated against a table containing 300k rows and index on date column.

As for the GROUP BY clause, I tested the three variants against the above mentioned table; here are the results:

SELECT YEAR(date_column), MONTH(date_column), COUNT(*)
FROM date_table
GROUP BY YEAR(date_column), MONTH(date_column)
-- codelogic
-- average 0.250 sec.

SELECT YEAR(date_column), MONTH(date_column), COUNT(*)
FROM date_table
GROUP BY DATE_FORMAT(date_column, '%Y%m')
-- Andriy M
-- average 0.468 sec.

SELECT YEAR(date_column), MONTH(date_column), COUNT(*)
FROM date_table
GROUP BY EXTRACT(YEAR_MONTH FROM date_column)
-- fu-chi
-- average 0.203 sec.

The last one is the winner.

Answer 14

If you want to get a monthly statistics with row counts per month of each year ordered by latest month, then try this:

SELECT count(id),
      YEAR(record_date),
      MONTH(record_date) 
FROM `table` 
GROUP BY YEAR(record_date),
        MONTH(record_date) 
ORDER BY YEAR(record_date) DESC,
        MONTH(record_date) DESC

Answer 15

I tried using the 'WHERE' statement above, I thought its correct since nobody corrected it but I was wrong; after some searches I found out that this is the right formula for the WHERE statement so the code becomes like this:

SELECT COUNT(id)  
FROM stats  
WHERE YEAR(record_date) = 2009  
GROUP BY MONTH(record_date)

Answer 16

GROUP BY DATE_FORMAT(record_date, '%Y%m')

---

Note (primarily, to potential downvoters). Presently, this may not be as efficient as other suggestions. Still, I leave it as an alternative, and a one, too, that can serve in seeing how faster other solutions are. (For you can't really tell fast from slow until you see the difference.) Also, as time goes on, changes could be made to MySQL's engine with regard to optimisation so as to make this solution, at some (perhaps, not so distant) point in future, to become quite comparable in efficiency with most others.

Answer 17

try this one

SELECT COUNT(id)
FROM stats
GROUP BY EXTRACT(YEAR_MONTH FROM record_date)

EXTRACT(unit FROM date) function is better as less grouping is used and the function return a number value.

Comparison condition when grouping will be faster than DATE_FORMAT function (which return a string value). Try using function|field that return non-string value for SQL comparison condition (WHERE, HAVING, ORDER BY, GROUP BY).

Answer 18

If you want to group by date in MySQL then use the code below:

 SELECT COUNT(id)
 FROM stats
 GROUP BY DAYOFMONTH(record_date)

Hope this saves some time for the ones who are going to find this thread.

Answer 19

GROUP BY YEAR(record_date), MONTH(record_date)

Check out the date and time functions in MySQL.