按月/年计算总条目数的 SQL 查询

Question

I am trying to count the total number of entries in my SQL table for each month.

CREATE TABLE table1
    (`ID` int, `date` date, `job` varchar)
;

INSERT INTO table1
    (`ID`, `date`, `job`)
VALUES
    (1, '2019-01-01', job A),
    (2, '2019-01-03', job B),
    (3, '2019-02-02', job C),
    (4, '2019-04-05', job D),
    (5, '2019-05-03', job E),
    (6, '2019-07-07', job F)
;

Select
DATE_FORMAT(`date`,'%M %Y') MontnameYear,
COUNT(job) counter
FROM table1
GROUP BY DATE_FORMAT(`date`,'%M %Y')
ORDER by mdate;

I have tried various different variations of the above but nothing that gets me a count for each month. I have a feeling that I am missing something obvious but cant see it :-(

Any help would be great

Answer 1

You query looks fine, apart from the group by clause, that refers to a column alias that does not exist in the query (that's a syntax error).

Consider:

Select
    DATE_FORMAT(`date`,'%M %Y') MontnameYear,
    COUNT(*) counter
FROM table1
GROUP BY DATE_FORMAT(`date`,'%M %Y')
ORDER by MIN(`date`)

Demo on DB FIddle :

MontnameYear  | counter
:------------ | ------:
January 2019  |       2
February 2019 |       1
April 2019    |       1
May 2019      |       1
July 2019     |       1

Side notes: your sample script has flaws:

• it is mandatory to give a length to a varchar column (say, varchar(10) )
• strings such as job A must be surrounded with single quotes