让 mySQL MONTH() 使用前导零？
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Get mySQL MONTH() to use leading zeros?
提问by jerrygarciuh
How do I specify to mySQL's MONTH() function to return '08' instead of 8 in this query?
如何指定 mySQL 的 MONTH() 函数在此查询中返回 '08' 而不是 8？
I'd like the sort to work datewise. Currently getting results for date like
我希望这种工作能按时工作。目前正在获得类似日期的结果
2006-9
2007-1
2007-10
2007-11
current query:
当前查询：
SELECT COUNT(*), CONCAT(YEAR(`datetime_added`), '-', MONTH(`datetime_added`)) as date FROM `person` WHERE (email = '' OR email IS NULL)
GROUP BY date
ORDER BY date ASC
回答by Mchl
Use the following instead:
请改用以下内容：
DATE_FORMAT(`datetime_added`,'%Y-%m')
Explanation:
解释：
DATE_FORMAT()function lets you format the date anyway you like using specifiers described in the table below (taken verbatim from documentation). So a format string '%Y-%m'means: "A full year (4 digits), followed by a dash (-), followed by a two-digit month number".
DATE_FORMAT()函数允许您使用下表中描述的说明符以您喜欢的任何方式格式化日期（逐字取自文档）。所以格式字符串的'%Y-%m'意思是：“一个完整的年份（4 位数字），后跟一个破折号 ( -)，然后是一个两位数的月份数字”。
Note that you can specify the language used for day/month names by setting lc_time_namessystem variable. Extremely useful. Refer to documentationfor more details.
请注意，您可以通过设置lc_time_names系统变量来指定用于日/月名称的语言。非常有用。有关更多详细信息，请参阅文档。
Specifier Description
%a Abbreviated weekday name (Sun..Sat)
%b Abbreviated month name (Jan..Dec)
%c Month, numeric (0..12)
%D Day of the month with English suffix (0th, 1st, 2nd, 3rd, …)
%d Day of the month, numeric (00..31)
%e Day of the month, numeric (0..31)
%f Microseconds (000000..999999)
%H Hour (00..23)
%h Hour (01..12)
%I Hour (01..12)
%i Minutes, numeric (00..59)
%j Day of year (001..366)
%k Hour (0..23)
%l Hour (1..12)
%M Month name (January..December)
%m Month, numeric (00..12)
%p AM or PM
%r Time, 12-hour (hh:mm:ss followed by AM or PM)
%S Seconds (00..59)
%s Seconds (00..59)
%T Time, 24-hour (hh:mm:ss)
%U Week (00..53), where Sunday is the first day of the week
%u Week (00..53), where Monday is the first day of the week
%V Week (01..53), where Sunday is the first day of the week; used with %X
%v Week (01..53), where Monday is the first day of the week; used with %x
%W Weekday name (Sunday..Saturday)
%w Day of the week (0=Sunday..6=Saturday)
%X Year for the week where Sunday is the first day of the week, numeric, four digits; used with %V
%x Year for the week, where Monday is the first day of the week, numeric, four digits; used with %v
%Y Year, numeric, four digits
%y Year, numeric (two digits)
%% A literal “%” character
%x x, for any “x” not listed above
回答by Dani
You can use padding like
你可以使用填充像
SELECT
COUNT(*),
CONCAT(YEAR(`datetime_added`), '-', LPAD(MONTH(`datetime_added`), 2, '0')) as date
FROM `person`
WHERE (email = '' OR email IS NULL)
GROUP BY date
ORDER BY date ASC
回答by Oh Chin Boon
DATE_FORMAT(`datetime_added`,'%Y - %m')
回答by Jeremy Holovacs
MONTH() returns an integer, so of course there's no leading zero. You will need to convert it to a string, left-pad the '0' and take the last 2 characters.
MONTH() 返回一个整数，所以当然没有前导零。您需要将其转换为字符串，左填充 '0' 并取最后 2 个字符。
