MySQL的日期函数较多，只需要掌握常用的即可，常用的日期或时间函数参考如下的表格：
表 STYLEREF 1 \s 4- SEQ 表 * ARABIC \s 1 1 MySQL的日期函数
| 函数 | 函数功能描述 | 函数举例 |
|---|---|---|
| DAYOFWEEK(DATE) | 返回DATE的星期索引（1= Sunday，2= Monday，... 7=Saturday） | mysql> SELECT DAYOFWEEK('2016-05-24');+-------------------------+ |
| DAYOFYEAR(DATE) | 返回DATE是一年中的第几天，范围为1到366 | mysql> SELECT DAYOFYEAR('2016-05-24');+-------------------------+ |
| HOUR(TIME)/MINUTE(TIME)/SECOND(TIME) | 返回TIME的小时值/分钟值/秒值，范围为0到23 | mysql> SELECT HOUR('10:05:03'),MINUTE('10:05:03'),SECOND('10:05:03');+------------------+--------------------+--------------------+ |
| DATE_FORMAT(DATE,FORMAT) | 依照FORMAT字符串格式化DATE值，修饰符的含义：%M：月的名字（January..December）%W：星期的名字（Sunday..Saturday）%D：有英文后缀的某月的第几天（0th，1st，2nd，3rd等） %Y：4位数字年份%y：2位数字年份 %m：月，数字（00..12）%c：月，数字（0..12） %d：代表月份中的天数，格式为（00……31）%e：代表月份中的天数，格式为（0……31） %x：周值的年份，星期一是一个星期的第一天，数字的，4位，与“%v”一同使用%a：缩写的星期名（Sun..Sat） %H：小时（00..23）%k：小时（0..23）%h：小时（01..12）%I：小时（01..12）%l：小时（1..12） %i：代表分钟， 格式为(00……59) 。只有这一个代表分钟，大写的I不代表分钟代表小时 %r：代表 时间，格式为12 小时（hh:mm:ss [AP]M)）%T：代表 时间，格式为24 小时（hh:mm:ss） %S：秒（00..59）%s：秒（00..59） %p：AM或PM%w：一周中的天数（0=Sunday..6=Saturday） | mysql> SELECT DATE_FORMAT('2016-05-24', '%W %M %Y');+---------------------------------------+ |
| STR_TO_DATE() | 将字符串转换为日期类型 | mysql> SELECT STR_TO_DATE('04/31/2004', '%m/%d/%Y');+---------------------------------------+ |
| CURDATE()/CURRENT_DATE | 以“YYYY-MM-DD”或“YYYYMMDD”格式返回当前的日期值 | mysql> SELECT CURDATE(),CURRENT_DATE;+------------+--------------+ |
| CURTIME()/CURRENT_TIME | 以“HH:MM:SS”或“HHMMSS”格式返回当前的时间值 | mysql> SELECT CURTIME(),CURRENT_TIME();+-----------+----------------+ |
| NOW()/SYSDATE()/CURRENT_TIMESTAMP | 以“YYYY-MM-DD HH:MM:SS”或“YYYYMMDDHHMMSS”格式返回当前的日期时间值 | mysql> SELECT NOW(),SYSDATE(),CURRENT_TIMESTAMP;+---------------------+---------------------+---------------------+ |
| SEC_TO_TIME(NUMBER) | 以“HH:MM:SS”或“HHMMSS”格式返回入参值被转换到时分秒后的值 | mysql> SELECT SEC_TO_TIME(2378);+-------------------+ |
| TIME_TO_SEC(TIME) | 将参数TIME转换为秒数后返回 | mysql> SELECT TIME_TO_SEC('22:23:00');+-------------------------+ |
其它的函数请查阅官方文档。
真题1、MySQL中的字符串和日期相互转化的函数是什么？
答案：MySQL中日期转换为字符串使用DATE_FORMAT函数，相当于Oracle中的TO_CHAR函数，而将字符串转换为日期格式，使用的函数为STR_TO_DATE，相当于Oracle中的TO_DATE函数。
STR_TO_DATE函数的使用示例如下所示：
select str_to_date('09/01/2009','%m/%d/%Y');
select str_to_date('20140422154706','%Y%m%d%H%i%s');
select str_to_date('2014-04-22 15:47:06','%Y-%m-%d %H:%i:%s');
12.7 Date and Time Functions
This section describes the functions that can be used to manipulate temporal values. See Section 11.3, “Date and Time Types”, for a description of the range of values each date and time type has and the valid formats in which values may be specified.
Table 12.13 Date and Time Functions
| 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 |
| Name | Description |
|---|
