#703 MySQL 时间相关函数汇总

MySQL 2021-11-16
Name Description
ADDDATE() Add time values (intervals) to a date value
ADDTIME() Add time
CONVERT_TZ() Convert from one time zone to another
CURDATE() Return the current date
CURRENT_DATE(),
CURRENT_DATE		 Synonyms for CURDATE()
CURRENT_TIME(),
CURRENT_TIME		 Synonyms for CURTIME()
CURRENT_TIMESTAMP(),
CURRENT_TIMESTAMP		 Synonyms for NOW()
CURTIME() Return the current time
DATE() Extract the date part of a date or datetime expression
DATE_ADD() Add time values (intervals) to a date value
DATE_FORMAT() Format date as specified
DATE_SUB() Subtract a time value (interval) from a date
DATEDIFF() Subtract two dates
DAY() Synonym for DAYOFMONTH()
DAYNAME() Return the name of the weekday
DAYOFMONTH() Return the day of the month (0-31)
DAYOFWEEK() Return the weekday index of the argument
DAYOFYEAR() Return the day of the year (1-366)
EXTRACT() Extract part of a date
FROM_DAYS() Convert a day number to a date
FROM_UNIXTIME() Format Unix timestamp as a date
GET_FORMAT() Return a date format string
HOUR() Extract the hour
LAST_DAY Return the last day of the month for the argument
LOCALTIME(),
LOCALTIME		 Synonym for NOW()
LOCALTIMESTAMP,
LOCALTIMESTAMP()		 Synonym for NOW()
MAKEDATE() Create a date from the year and day of year
MAKETIME() Create time from hour, minute, second
MICROSECOND() Return the microseconds from argument
MINUTE() Return the minute from the argument
MONTH() Return the month from the date passed
MONTHNAME() Return the name of the month
NOW() Return the current date and time
PERIOD_ADD() Add a period to a year-month
PERIOD_DIFF() Return the number of months between periods
QUARTER() Return the quarter from a date argument
SEC_TO_TIME() Converts seconds to 'hh:mm:ss' format
SECOND() Return the second (0-59)
STR_TO_DATE() Convert a string to a date
SUBDATE() Synonym for DATE_SUB() when invoked with three arguments
SUBTIME() Subtract times
SYSDATE() Return the time at which the function executes
TIME() Extract the time portion of the expression passed
TIME_FORMAT() Format as time
TIME_TO_SEC() Return the argument converted to seconds
TIMEDIFF() Subtract time
TIMESTAMP() With a single argument, this function returns the date or datetime expression;
with two arguments, the sum of the arguments
TIMESTAMPADD() Add an interval to a datetime expression
TIMESTAMPDIFF() Subtract an interval from a datetime expression
TO_DAYS() Return the date argument converted to days
TO_SECONDS() Return the date or datetime argument converted to seconds since Year 0
UNIX_TIMESTAMP() Return a Unix timestamp
UTC_DATE() Return the current UTC date
UTC_TIME() Return the current UTC time
UTC_TIMESTAMP() Return the current UTC date and time
WEEK() Return the week number
WEEKDAY() Return the weekday index
WEEKOFYEAR() Return the calendar week of the date (1-53)
YEAR() Return the year
YEARWEEK() Return the year and week
  • ADDDATE(date, INTERVAL expr unit), ADDDATE(expr, days)
SELECT WEEK(CURRENT_DATE());

SELECT '2021-01-01' AS `Date`, DAYNAME('2021-01-01'), DAYOFWEEK('2021-01-01'), WEEK('2021-01-01'), WEEKDAY('2021-01-01'), WEEKOFYEAR('2021-01-01'), YEARWEEK('2021-01-01')
UNION SELECT '2021-01-06' AS `Date`, DAYNAME('2021-01-04'), DAYOFWEEK('2021-01-04'), WEEK('2021-01-04'), WEEKDAY('2021-01-04'), WEEKOFYEAR('2021-01-04'), YEARWEEK('2021-01-04')
UNION SELECT '2021-01-08' AS `Date`, DAYNAME('2021-01-08'), DAYOFWEEK('2021-01-08'), WEEK('2021-01-08'), WEEKDAY('2021-01-08'), WEEKOFYEAR('2021-01-08'), YEARWEEK('2021-01-08');
-- weekday: monday 0, tuesday 1 ... sunday 6

#701 元宇宙与人类的未来

元宇宙 星辰大海 2021-11-15

对于近日大火的“元宇宙”概念，被称为“中国第一位元宇宙架构师”刘慈欣曾表示，元宇宙将是整个人类文明的一次内卷，而内卷的封闭系统的熵值总归是要趋于最大的。所以元宇宙最后就是引导人类走向死路一条。

#697 最近工作的一次总结

个人 工作 开发者 2021-11-13

最近两周开发了一个功能，其实质就是做个数据统计，没啥好说的。
我是在没有产品设计的前提下开始工作，产品的设计反倒有一点依赖我所能提供的数据。
而且，和以往自己写功能逻辑不通的是，我这次只管提供数据和方案，业务逻辑的实现由别人来做。
工作过程中遇到了一些问题，这里做个总结（复盘）。

#696 Golang 历史回顾

Golang 2021-11-09
版本 日期 备注
go1.17 2021-08-16
go1.16 2021-02-16
go1.15 2020-08-11
go1.14 2020-02-25
go1.13 2019-09-03 Go modules 成为默认
go1.12 2019-02-25
go1.11 2018-08-24 Go modules 引入
go1.10 2018-02-16
go1.9 2017-08-24
go1.8 2017-02-16
go1.7 2016-08-15 context
go1.6 2016-02-17 net/http 支持 HTTP/2
go1.5 2015-08-19 并发 GC
go1.4 2014-12-10
go1.3 2014-06-18
go1.2 2013-12-01
go1.1 2013-05-13
go1 2012-03-28

参考资料与拓展阅读

#695 穿越必备

阅读 2021-11-04

知乎上别人安利的几本奇书, 据说穿越的时候如果带了这几本书可以直接准备年号了。