Date and time functions are mainly used to process date and time values , The general date function uses date Type , You can also use datetime perhaps timestamp Parameters of type , But the time part of these values is ignored .

Function to get the current date

curdate() and current_date() The function does the same thing , Set the current date according to yyyy-mm-dd or yyyymmdd The value of the format returns .

mysql> select curdate(), current_date(), curdate() + 0;
+------------+----------------+---------------+
| curdate()  | current_date() | curdate() + 0 |
+------------+----------------+---------------+
| 2022-07-12 | 2022-07-12     |      20220712 |
+------------+----------------+---------------+
1 row in set (0.00 sec)

mysql>

See from above , The functions of the two functions are the same , Both return the same current system date .

curdate()+0 Converts the current date to numeric .

Function to get the current time

curtime() and current_time() The function does the same thing , Change the current time to hh:mm:ss perhaps hhmmss The format returns .

mysql> select curtime(), current_time(), curtime()+0;
+-----------+----------------+-------------+
| curtime() | current_time() | curtime()+0 |
+-----------+----------------+-------------+
| 21:32:25  | 21:32:25       |      213225 |
+-----------+----------------+-------------+
1 row in set (0.00 sec)

mysql>

See from above , The functions of the two functions are the same , They all go back on the current time of the same system .

Function to get the current date and time

current_timestamp()、localtime()、now() and sysdate() this 4 The functions have the same function , Are values that return the current date and time .

mysql> select current_timestamp(), localtime(), now(), sysdate();
+---------------------+---------------------+---------------------+---------------------+
| current_timestamp() | localtime()         | now()               | sysdate()           |
+---------------------+---------------------+---------------------+---------------------+
| 2022-07-12 21:34:52 | 2022-07-12 21:34:52 | 2022-07-12 21:34:52 | 2022-07-12 21:34:52 |
+---------------------+---------------------+---------------------+---------------------+
1 row in set (0.00 sec)

mysql>

See from above ,4 The results returned by the two functions are the same .

UNIX Time stamp function

UNIX_TIMESTAMP(date) If there is no parameter call , Returns a UNIX Time stamp （‘1970-01-01 00:00:00’GMT Seconds after that ） As an unsigned integer .

among ,GMT（Green wich mean time） Greenwich mean time . If use date To call UNIX_TIMESTAMP(), It will change the parameter value to 1970-01-0100:00:00GMT The number of seconds after the return .

date It could be a DATE character string 、DATETIME character string 、TIMESTAMP Or a local time YYMMDD or YYYYMMDD Number in format .

mysql> select unix_timestamp(), unix_timestamp(now()), now();
+------------------+-----------------------+---------------------+
| unix_timestamp() | unix_timestamp(now()) | now()               |
+------------------+-----------------------+---------------------+
|       1657633074 |            1657633074 | 2022-07-12 21:37:54 |
+------------------+-----------------------+---------------------+
1 row in set (0.00 sec)

mysql>

from_unixtime(date) Function unix Time stamp is converted to normal format , And unix_timestamp(date) Functions are inverse functions to each other . Example ：

mysql> select from_unixtime('1657633074');
+-----------------------------+
| from_unixtime('1657633074') |
+-----------------------------+
| 2022-07-12 21:37:54.000000  |
+-----------------------------+
1 row in set (0.00 sec)

mysql>

return UTC Function of date

utc_date() Function returns the current utc( World standard time ) Date value , The format for yyyy-mm-dd perhaps yyyymmdd;

mysql> select utc_date(), utc_date()+0;
+------------+--------------+
| utc_date() | utc_date()+0 |
+------------+--------------+
| 2022-07-12 |     20220712 |
+------------+--------------+
1 row in set (0.00 sec)

mysql>

return UTC A function of time

utc_time() Returns the current utc Time value , The format is hh:mm:ss perhaps hhmmss;

mysql> select utc_time(), utc_time()+0;
+------------+--------------+
| utc_time() | utc_time()+0 |
+------------+--------------+
| 13:43:24   |       134324 |
+------------+--------------+
1 row in set (0.00 sec)

mysql>

Function to get month MONTH(date) and MONTHNAME(date)

month(date) The function returns date The corresponding month .

mysql> select month('2022-12-12') as coll, month('20221212') as coll_1, month('221212') as coll_2;
+------+--------+--------+
| coll | coll_1 | coll_2 |
+------+--------+--------+
|   12 |     12 |     12 |
+------+--------+--------+
1 row in set (0.00 sec)

mysql>

monthname(date) Function returns the date date The full English name of the corresponding month ;

mysql> select monthname('2022-12-12'), monthname('20221212'), monthname('221212');
+-------------------------+-----------------------+---------------------+
| monthname('2022-12-12') | monthname('20221212') | monthname('221212') |
+-------------------------+-----------------------+---------------------+
| December                | December              | December            |
+-------------------------+-----------------------+---------------------+
1 row in set (0.00 sec)

mysql>

Get the function of week DAYNAME(d)、DAYOFWEEK(d) and WEEKDAY(d)

dayname(d) The function returns d English name of the corresponding working day ;

mysql> select dayname('2022-07-12');
+-----------------------+
| dayname('2022-07-12') |
+-----------------------+
| Tuesday               |
+-----------------------+
1 row in set (0.00 sec)

mysql>

dayofweek(d) The function returns d Index of the corresponding week （ Location ,1 Means Sunday ,2 It means Monday , And so on ,7 It means Saturday ）;

mysql> select dayofweek('2022-07-12') as coll, dayofweek('2022-07-13') as coll_1;
+------+--------+
| coll | coll_1 |
+------+--------+
|    3 |      4 |
+------+--------+
1 row in set (0.00 sec)

mysql>

weekday(d) return d Corresponding weekday index ：0 It means Monday ,1 Tuesday , And so on ,6 Means Sunday .

mysql> select weekday('2022-07-12') as coll, weekday('2022-07-13') as coll_1;
+------+--------+
| coll | coll_1 |
+------+--------+
|    1 |      2 |
+------+--------+
1 row in set (0.00 sec)

mysql>

Get the function of week WEEK(d) and WEEKOFYEAR(d)

week(d) Calculate the date d It's the week of the year .

week() The two parameter form of allows you to specify whether the week begins on Sunday or Monday , And whether the return value range is 0_{53 perhaps 1}53. if mode Parameters are omitted , Then use default_week_format The value of the system argument , Here's the picture ：

for example ： Use week() The function queries which week of the year the specified date is ;

mysql> select week('2022-07-13'), week('2022-01-01'), week('2022-09-18');
+--------------------+--------------------+--------------------+
| week('2022-07-13') | week('2022-01-01') | week('2022-09-18') |
+--------------------+--------------------+--------------------+
|                 28 |                  0 |                 38 |
+--------------------+--------------------+--------------------+
1 row in set (0.00 sec)

mysql>

weekofyear(d) Calculate the week of the year in which a day is located , The scope is 1~53, amount to week(d,3);

for example ： Use weekofyear(d) The query specifies the week of the year ;

mysql> select weekofyear('2022-07-13'), week('2022-07-13', 3);
+--------------------------+-----------------------+
| weekofyear('2022-07-13') | week('2022-07-13', 3) |
+--------------------------+-----------------------+
|                       28 |                    28 |
+--------------------------+-----------------------+
1 row in set (0.00 sec)

mysql>

As can be seen from the above , The two functions return the same result .

Function to get the number of days DAYOFYEAR(d) and DAYOFMONTH(d)

dayofyear(d) The function returns d It's the day of the year , The scope is 1~366;

for example ： Use dayofyear() Function returns the position of the specified date in a year ;

mysql> select dayofyear('2022-07-13'), dayofyear('2022-01-01');
+-------------------------+-------------------------+
| dayofyear('2022-07-13') | dayofyear('2022-01-01') |
+-------------------------+-------------------------+
|                     194 |                       1 |
+-------------------------+-------------------------+
1 row in set (0.00 sec)

mysql>

dayofmonth(d) The function returns d It's the day of the month , The scope is 1~31;

for example ： Use dayofmonth() Function returns the position of the specified date in a month , There must be a specific year .

mysql> select dayofmonth('2022-07-13'), dayofmonth('220713'), dayofmonth('0713');
+--------------------------+----------------------+--------------------+
| dayofmonth('2022-07-13') | dayofmonth('220713') | dayofmonth('0713') |
+--------------------------+----------------------+--------------------+
|                       13 |                   13 |               NULL |
+--------------------------+----------------------+--------------------+
1 row in set, 1 warning (0.00 sec)

mysql>

Get year 、 quarter 、 Hours 、 As a function of minutes and seconds

year(date) return date Corresponding year , The scope is 1970~2069;

mysql> select year('2022-07-13'), year('20330909');
+--------------------+------------------+
| year('2022-07-13') | year('20330909') |
+--------------------+------------------+
|               2022 |             2033 |
+--------------------+------------------+
1 row in set (0.00 sec)

mysql>

tip ：

00~69 Convert to 2000~2069,70~99 Convert to 1970~1999.

quarter(date) return date The corresponding quarterly value of the year , The scope is 1~4;

mysql> select quarter('2022-07-13'), quarter('20330101');
+-----------------------+---------------------+
| quarter('2022-07-13') | quarter('20330101') |
+-----------------------+---------------------+
|                     3 |                   1 |
+-----------------------+---------------------+
1 row in set (0.00 sec)

mysql>

minute(time) return time The corresponding number of minutes , The scope is 0~59.

mysql> select minute('2022-07-13 09:09:09'), minute('06:06:06');
+-------------------------------+--------------------+
| minute('2022-07-13 09:09:09') | minute('06:06:06') |
+-------------------------------+--------------------+
|                             9 |                  6 |
+-------------------------------+--------------------+
1 row in set (0.00 sec)

mysql>

second(time) return time The corresponding number of seconds , The scope is 0~59.

mysql> select second('2022-07-13 09:09:09'), second('06:06:06');
+-------------------------------+--------------------+
| second('2022-07-13 09:09:09') | second('06:06:06') |
+-------------------------------+--------------------+
|                             9 |                  6 |
+-------------------------------+--------------------+
1 row in set (0.00 sec)

mysql>

Function to get the specified value of the date EXTRACT(type from date)

extract(type from date) The time interval type specifier used by the function is the same as date_add() or date_sub() identical , But it takes a part from the date , Instead of performing date operations .

mysql> select extract(year from '2022-07-13') as coll, extract(year_month from '2022-07-13') as coll_1, extract(day_minute from '2022-07-13 09:08:07') as coll_2;
+------+--------+--------+
| coll | coll_1 | coll_2 |
+------+--------+--------+
| 2022 | 202207 | 130908 |
+------+--------+--------+
1 row in set (0.00 sec)

mysql>

type For different values , The values returned are different ：

• year： Only return year value

• year_month： Return year and month

• day_minute： Return day 、 Hours and minutes

Time and second conversion function

time_to_sec(time) Returns the number of seconds converted time Parameters .

Change the formula to ： Hours *3600+ minute *60+ second

mysql> select time_to_sec('09:09:09');
+-------------------------+
| time_to_sec('09:09:09') |
+-------------------------+
|                   32949 |
+-------------------------+
1 row in set (0.00 sec)

mysql>

sec_to_time(seconds) Return is converted into hours 、 Minutes and seconds seconds Parameter values , The format for hh:mm:ss perhaps hhmmss.

mysql> select time_to_sec('09:09:09'), sec_to_time(32949);
+-------------------------+--------------------+
| time_to_sec('09:09:09') | sec_to_time(32949) |
+-------------------------+--------------------+
|                   32949 | 09:09:09           |
+-------------------------+--------------------+
1 row in set (0.00 sec)

mysql>

You can see from above ,time_to_sec and sec_to_time They're inverse functions to each other .

A function that calculates the date and time

The functions for calculating date and time are ：

• date_add()

• adddate()

• date_sub()

• subdate()

• addtime()

• subtime()

• date_diff()

stay date_add(date, interval expr type) and date_sub(date, interval expr type) in ：

• date It's a datetime perhaps date value , Used to specify the starting time .

• expr It's an expression , Used to specify the interval value added or subtracted from the start date . For time intervals with negative values ,expr You can use a symbol - start .

• type For the keyword , Indicates how the expression is interpreted .

• 

if date The parameter is one date value , The calculation will only include year、month and day part （ There is no time part ）, The result is a date value , otherwise , The result will be a datetime value .

date_add(date, interval expr type) and adddate(date, intervar expr type) Two functions have the same function , Perform the addition of dates .

mysql> select date_add('2022-07-13 09:09:09', interval 1 second) as coll, adddate('2022-07-13 09:09:09', interval 1 second) as coll_1, date_add('2022-07-13 09:09:09', interval '1:1' minute_second) as coll_2;
+---------------------+---------------------+---------------------+
| coll                | coll_1              | coll_2              |
+---------------------+---------------------+---------------------+
| 2022-07-13 09:09:10 | 2022-07-13 09:09:10 | 2022-07-13 09:10:10 |
+---------------------+---------------------+---------------------+
1 row in set (0.00 sec)

mysql>

date_sub(date, interval expr type) perhaps subdate(date, interval expr type) Two functions have the same function , Perform the subtraction of the date .

mysql> select date_sub('2022-07-13 09:09:09', interval 31 day) as coll, subdate('2022-07-13 09:09:09', interval 31 day) as coll_1, date_sub('2022-07-13 09:09:09', interval '0 0:1:1' day_second) as coll_2;
+---------------------+---------------------+---------------------+
| coll                | coll_1              | coll_2              |
+---------------------+---------------------+---------------------+
| 2022-06-12 09:09:09 | 2022-06-12 09:09:09 | 2022-07-13 09:08:08 |
+---------------------+---------------------+---------------------+
1 row in set (0.00 sec)

mysql>

addtime(date, expr) Function will expr Value added to date, And return the modified value ,date Value a date or datetime expression , and expr It's a time expression .

mysql> select adddate('2022-07-13 09:09:09', '1:1:1'), addtime('09:09:09', '1:1:20');
+-----------------------------------------+-------------------------------+
| adddate('2022-07-13 09:09:09', '1:1:1') | addtime('09:09:09', '1:1:20') |
+-----------------------------------------+-------------------------------+
| 2022-07-14 09:09:09                     | 10:10:29                      |
+-----------------------------------------+-------------------------------+
1 row in set, 1 warning (0.00 sec)

mysql>

subtime(date,expr) Function will date subtract expr value , And return the modified value .

among ,date Is a date or date time expression , and expr It's a time expression .

mysql> select subtime('2020-07-13 09:09:09', '1:1:1 1:1:1'), subtime('2022-07-13 09:09:09', '1:1:1');
+-----------------------------------------------+-----------------------------------------+
| subtime('2020-07-13 09:09:09', '1:1:1 1:1:1') | subtime('2022-07-13 09:09:09', '1:1:1') |
+-----------------------------------------------+-----------------------------------------+
| 2020-07-13 08:08:08                           | 2022-07-13 08:08:08                     |
+-----------------------------------------------+-----------------------------------------+
1 row in set, 2 warnings (0.00 sec)

mysql>

You can see from above , Only the time is calculated , The date is not counted .

Use datediff() Function to calculate the number of days between two dates ;

mysql> select datediff('2022-07-13 09:09:09', '2022-01-01') as coll, datediff('2022-07-13 09:09:09', '2022-07-10 08:08:08');
+------+--------------------------------------------------------+
| coll | datediff('2022-07-13 09:09:09', '2022-07-10 08:08:08') |
+------+--------------------------------------------------------+
|  193 |                                                      3 |
+------+--------------------------------------------------------+
1 row in set (0.00 sec)

mysql>

Functions that format dates and times

date_format(date,format) according to format Display... In the specified format date value .

The main format The format is as follows ：

Example ： Use date_format() Function to format the output date and time values ;

mysql> select date_format('2022-07-13 09:08:07', '%W %M %Y') as coll, date_format('2022-07-13 09:08:07', '%D %y %a %d %m %b %j') as coll_1;
+---------------------+---------------------------+
| coll                | coll_1                    |
+---------------------+---------------------------+
| Wednesday July 2022 | 13th 22 Wed 13 07 Jul 194 |
+---------------------+---------------------------+
1 row in set (0.00 sec)

mysql>

time_format(time, format) According to the expression format The request shows the time time .

expression format Specifies the format of the display . because time_format(time, format) Only processing time , therefore format Only use time format .

Example ： Use time_format() Function format input time value .

mysql> select time_format('13:14:15', '%H %k %h %I %l');
+-------------------------------------------+
| time_format('13:14:15', '%H %k %h %I %l') |
+-------------------------------------------+
| 13 13 01 01 1                             |
+-------------------------------------------+
1 row in set (0.00 sec)

mysql>

get_format(val_typr, format_type) Return the display format of date time string ：

• val_type Represents the date data type , Include date、datetime and time;

• format_type Indicates the format display type , Include eur、interval、iso、jis、usa.

get_format The display format of the returned string based on the combination of two value types is as follows ：

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Example ： Use get_format() Function to display format strings under different format types .

mysql> select get_format(date, 'eur'), get_format(datetime, 'jis');
+-------------------------+-----------------------------+
| get_format(date, 'eur') | get_format(datetime, 'jis') |
+-------------------------+-----------------------------+
| %d.%m.%Y                | %Y-%m-%d %H:%i:%s           |
+-------------------------+-----------------------------+
1 row in set (0.00 sec)

mysql> 
mysql> select date_format('2022-07-13 09:08:07', get_format(datetime, 'jis')) as coll, date_format('2022-07-13 09:08:07', get_format(date, 'usa')) as coll_1;
+---------------------+------------+
| coll                | coll_1     |
+---------------------+------------+
| 2022-07-13 09:08:07 | 07.13.2022 |
+---------------------+------------+
1 row in set (0.00 sec)

mysql>

thus , In this paper, the end .

For more information, go to VX official account “ Operation and maintenance home ” , Get the latest article .

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