Tutorial on principles and applications of database system (054) -- MySQL query (16): usage of date time function

Database system principle and Application Tutorial （054）—— MySQL Inquire about （ sixteen ）： Usage of date time function

Using functions when querying can construct more flexible query conditions ,MySQL Provides functions for processing dates and times .

One 、 Create data table

The data table used for query is as follows ：

--  Table structure 
mysql> desc student;
+--------+--------------+------+-----+---------+-------+
| Field  | Type         | Null | Key | Default | Extra |
+--------+--------------+------+-----+---------+-------+
| s_id   | char(5)      | NO   | PRI | NULL    |       |
| s_name | char(20)     | YES  |     | NULL    |       |
| gender | char(1)      | YES  |     | NULL    |       |
| birth  | datetime     | YES  |     | NULL    |       |
| phone  | char(20)     | YES  |     | NULL    |       |
| addr   | varchar(100) | YES  |     | NULL    |       |
+--------+--------------+------+-----+---------+-------+
6 rows in set (0.10 sec)

--  Table data 
mysql> select * from student;
+-------+-----------+--------+---------------------+-------------+-----------+
| s_id  | s_name    | gender | birth               | phone       | addr      |
+-------+-----------+--------+---------------------+-------------+-----------+
| S2011 |  Zhang Xiaogang     |  male      | 1999-12-03 00:00:00 | 13163735775 |  Xinyang City     |
| S2012 |  Liu Xiaoqing     |  Woman      | 1999-10-11 00:00:00 | 13603732255 |  Xinxiang City     |
| S2013 |  Cao mengde     |  male      | 1998-02-13 00:00:00 | 13853735522 |  Zhengzhou city     |
| S2014 |  Liu Yan       |  Woman      | 1998-06-24 00:00:00 | 13623735335 |  Zhengzhou city     |
| S2015 |  Liu Yan       |  Woman      | 1999-07-06 00:00:00 | 13813735225 |  Xinyang City     |
| S2016 |  Liu Ruofei     |  Woman      | 2000-08-31 00:00:00 | 13683735533 |  Kaifeng City     |
| S2021 |  Dong Wenhua     |  Woman      | 2000-07-30 00:00:00 | 13533735564 |  Kaifeng City     |
| S2022 |  Zhou Huajian     |  male      | 1999-05-25 00:00:00 | 13243735578 |  Zhengzhou city     |
| S2023 |  trump     |  male      | 1999-06-21 00:00:00 | 13343735588 |  Xinxiang City     |
| S2024 |  Obama     |  male      | 2000-10-17 00:00:00 | 13843735885 |  Xinyang City     |
| S2025 |  Zhou Jianhua     |  male      | 2000-08-22 00:00:00 | 13788736655 |  Kaifeng City     |
| S2026 |  Zhang Xueyou     |  male      | 1998-07-06 00:00:00 | 13743735566 |  Zhengzhou city     |
| S2031 |  Lee Myung Bak     |  Woman      | 1999-10-26 00:00:00 | 13643732222 |  Zhengzhou city     |
| S2032 |  Vinci     |  male      | 1999-12-31 00:00:00 | 13043731234 |  Zhengzhou city     |
+-------+-----------+--------+---------------------+-------------+-----------+
14 rows in set (0.00 sec)

Two 、 Function to query system date and time

Used to return the system date and time of the computer .

The syntax is as follows ：

--  Functions take no arguments 
-- CURDATE()  and  CURRENT_DATE()  The return values of the two functions are the same , All are the date returned to the system 
-- CURTIME()  and  CURRENT_TIME()  The return values of the two functions are the same , Are the return system time 
--  function  NOW()  Return the system date and time .
CURDATE()
CURRENT_DATE()
CURTIME()
CURRENT_TIME()
NOW()

for example ：

（1） Query the current date 、 Current time and current date time ：

mysql> select current_date(),current_time(),now() from dual;
+----------------+----------------+---------------------+
| current_date() | current_time() | now()               |
+----------------+----------------+---------------------+
| 2022-07-23     | 11:33:03       | 2022-07-23 11:33:03 |
+----------------+----------------+---------------------+
1 row in set (0.00 sec)

mysql> select curdate(),curtime(),now() from dual;
+------------+-----------+---------------------+
| curdate()  | curtime() | now()               |
+------------+-----------+---------------------+
| 2022-07-23 | 11:32:36  | 2022-07-23 11:32:36 |
+------------+-----------+---------------------+
1 row in set (0.00 sec)

（2） Query the student's age

--  Use  curdate()  function 
mysql> select s_id, s_name, year(curdate())-year(birth) age from student where addr=' Xinxiang City ';
+-------+-----------+------+
| s_id  | s_name    | age  |
+-------+-----------+------+
| S2012 |  Liu Xiaoqing     |   23 |
| S2023 |  trump     |   23 |
+-------+-----------+------+
2 rows in set (0.00 sec)

--  Use  current_date()  function 
mysql> select s_id, s_name, year(current_date())-year(birth) age from student where addr=' Xinxiang City ';
+-------+-----------+------+
| s_id  | s_name    | age  |
+-------+-----------+------+
| S2012 |  Liu Xiaoqing     |   23 |
| S2023 |  trump     |   23 |
+-------+-----------+------+
2 rows in set (0.00 sec)

--  Use  now()  function 
mysql> select s_id, s_name, year(now())-year(birth) age from student where addr=' Xinxiang City ';
+-------+-----------+------+
| s_id  | s_name    | age  |
+-------+-----------+------+
| S2012 |  Liu Xiaoqing     |   23 |
| S2023 |  trump     |   23 |
+-------+-----------+------+
2 rows in set (0.01 sec)

3、 ... and 、 Query the various components of the date and time

Return year in date time 、 month 、 Japan 、 when 、 branch 、 second 、 Day of week and other information .

The syntax is as follows ：

YEAR(datetime)        --  Returns the year in the date , Return value range from  1000  To  9999
MONTH(datetime)       --  Return the month in the date , Return value range from  1  To  12
MONTHNAME(datetime)   --  Returns the full name of the month in the date 
DAY(datetime)         --  Returns the day of the current month in the date , Return value range from  1  To  31
DAYOFMONTH(datetime)  --  And functions  DAY(datetime)  The usage is exactly the same 
DAYOFWEEK(datetime)   --  Returns the day of the week the current date is （ Numerical type ：1= Sunday ,2= Monday , ...,7= Saturday ）
DAYOFYEAR(datetime)   --  Returns the day of the year that the current date is , Return value range from  1  To  366
DAYNAME(datetime)     --  Returns the day of the week the current date is （ Character ： English words of date ）
QUARTER(datetime)     --  Returns the quarter in which the current date is , Return value range from  1  To  4
HOUR(datetime)        --  Returns the number of hours of the current time , Return value range from  0  To  23
MINUTE(datetime)      --  Returns the number of minutes of the current time , Return value range from  0  To  59
SECOND(datetime)      --  Returns the number of seconds of the current time , Return value range from  0  To  59
-- EXTRACT  Function USES  part  The parameter indicates which part of the date and time to return , namely ： year 、 month 、 Japan 、 when 、 branch 、 second 、 Day of week and other information 
-- part  The values of parameters are as follows ：YEAR（ year ）、MONTH（ month ）、DAY（ Japan ）、HOUR（ when ）、MINUTE（ branch ）、SECOND（ second ）
-- MICROSECOND（ millisecond ）、WEEK（ The weeks of the year ）、QUARTER（ What quarter ）
EXTRACT(part from datetime)

for example ：

（1） Examples of basic usage

--  Return the year in the date respectively 、 month 、 Japan 
mysql> select year(now()),month(now()),day(now()) from dual;
+-------------+--------------+------------+
| year(now()) | month(now()) | day(now()) |
+-------------+--------------+------------+
|        2022 |            7 |         23 |
+-------------+--------------+------------+
1 row in set (0.00 sec)

mysql> select EXTRACT(year from now()),EXTRACT(month from now()),EXTRACT(day from now()) 
       from dual;
+--------------------------+---------------------------+-------------------------+
| EXTRACT(year from now()) | EXTRACT(month from now()) | EXTRACT(day from now()) |
+--------------------------+---------------------------+-------------------------+
|                     2022 |                         7 |                      23 |
+--------------------------+---------------------------+-------------------------+
1 row in set (0.00 sec)

--  Respectively return the hours in time 、 branch 、 second 
mysql> select hour(now()),minute(now()),second(now()) from dual;
+-------------+---------------+---------------+
| hour(now()) | minute(now()) | second(now()) |
+-------------+---------------+---------------+
|          11 |            45 |            29 |
+-------------+---------------+---------------+
1 row in set (0.00 sec)

mysql> select EXTRACT(hour from now()),EXTRACT(minute from now()),EXTRACT(second from now()) 
       from dual;
+--------------------------+----------------------------+----------------------------+
| EXTRACT(hour from now()) | EXTRACT(minute from now()) | EXTRACT(second from now()) |
+--------------------------+----------------------------+----------------------------+
|                       11 |                         57 |                         34 |
+--------------------------+----------------------------+----------------------------+
1 row in set (0.00 sec)

--  Query the year in the current date 、 month 、 Japan 、 What day 
mysql> select year(now()),monthname(now()),dayofmonth(now()),dayofweek(now()),dayname(now()) 
    -> from dual;
+-------------+------------------+-------------------+------------------+----------------+
| year(now()) | monthname(now()) | dayofmonth(now()) | dayofweek(now()) | dayname(now()) |
+-------------+------------------+-------------------+------------------+----------------+
|        2022 | July             |                23 |                7 | Saturday       |
+-------------+------------------+-------------------+------------------+----------------+
1 row in set (0.02 sec)

--  The current date of query is the day of the year , What quarter 
mysql> select dayofyear(now()),quarter(now()) from dual;
+------------------+----------------+
| dayofyear(now()) | quarter(now()) |
+------------------+----------------+
|              204 |              3 |
+------------------+----------------+
1 row in set (0.00 sec)

mysql> select EXTRACT(quarter from now()) from dual;
+-----------------------------+
| EXTRACT(quarter from now()) |
+-----------------------------+
|                           3 |
+-----------------------------+
1 row in set (0.00 sec)

（2） Query the information of students born in the third quarter

mysql> select * from student where quarter(birth)=3;
+-------+-----------+--------+---------------------+-------------+-----------+
| s_id  | s_name    | gender | birth               | phone       | addr      |
+-------+-----------+--------+---------------------+-------------+-----------+
| S2015 |  Liu Yan       |  Woman      | 1999-07-06 00:00:00 | 13813735225 |  Xinyang City     |
| S2016 |  Liu Ruofei     |  Woman      | 2000-08-31 00:00:00 | 13683735533 |  Kaifeng City     |
| S2021 |  Dong Wenhua     |  Woman      | 2000-07-30 00:00:00 | 13533735564 |  Kaifeng City     |
| S2025 |  Zhou Jianhua     |  male      | 2000-08-22 00:00:00 | 13788736655 |  Kaifeng City     |
| S2026 |  Zhang Xueyou     |  male      | 1998-07-06 00:00:00 | 13743735566 |  Zhengzhou city     |
+-------+-----------+--------+---------------------+-------------+-----------+
5 rows in set (0.00 sec)

（3） Check the information of students whose birthdays are this month

mysql> select * from student where month(birth)=month(now());
+-------+-----------+--------+---------------------+-------------+-----------+
| s_id  | s_name    | gender | birth               | phone       | addr      |
+-------+-----------+--------+---------------------+-------------+-----------+
| S2015 |  Liu Yan       |  Woman      | 1999-07-06 00:00:00 | 13813735225 |  Xinyang City     |
| S2021 |  Dong Wenhua     |  Woman      | 2000-07-30 00:00:00 | 13533735564 |  Kaifeng City     |
| S2026 |  Zhang Xueyou     |  male      | 1998-07-06 00:00:00 | 13743735566 |  Zhengzhou city     |
+-------+-----------+--------+---------------------+-------------+-----------+
3 rows in set (0.00 sec)

（4） Check the student information of today's birthday

mysql> select * from student 
       where month(birth)=month(now()) and day(birth)=day(now());
Empty set (0.00 sec)

Four 、 A function that calculates the date and time

1、DATE_ADD() function

Add a date to a date time 、 Time unit .

The syntax is as follows ：

-- unit： date 、 Time unit , The value is ：YEAR（ year ）,MONTH（ month ）,DAY（ God ）,HOUR（ Hours ）,MINUTE（ minute ）,
-- SECOND（ second ）,WEEK（ week ）,QUARTER（ quarter ）
-- n： It's an integer . When  n  Greater than  0  when , Said to increase  n  Date time units , When  n  Less than  0  when , To reduce  n  Time units 
DATE_ADD(datetime, interval n unit)

for example ：

（1） Examples of basic usage

--  Query after the current date  2  year 、10  Months 、258  The date of day 
/* select now(), date_add(now(),interval 2 year) date1, date_add(now(),interval 10 month) date2, date_add(now(),interval 258 day) date3 from dual; */
mysql> select now(),
    ->        date_add(now(),interval 2 year) date1,
    ->        date_add(now(),interval 10 month) date2,
    ->        date_add(now(),interval 258 day) date3
    -> from dual;
+---------------------+---------------------+---------------------+---------------------+
| now()               | date1               | date2               | date3               |
+---------------------+---------------------+---------------------+---------------------+
| 2022-07-23 12:07:41 | 2024-07-23 12:07:41 | 2023-05-23 12:07:41 | 2023-04-07 12:07:41 |
+---------------------+---------------------+---------------------+---------------------+
1 row in set (0.00 sec)

--  Query before the current date  3  year 、20  Months 、558  The date of day 
/* select now(), date_add(now(),interval -3 year) date1, date_add(now(),interval -20 month) date2, date_add(now(),interval -558 day) date3 from dual; */
mysql> select now(),
    ->        date_add(now(),interval -3 year) date1,
    ->        date_add(now(),interval -20 month) date2,
    ->        date_add(now(),interval -558 day) date3
    -> from dual;
+---------------------+---------------------+---------------------+---------------------+
| now()               | date1               | date2               | date3               |
+---------------------+---------------------+---------------------+---------------------+
| 2022-07-23 12:09:13 | 2019-07-23 12:09:13 | 2020-11-23 12:09:13 | 2021-01-11 12:09:13 |
+---------------------+---------------------+---------------------+---------------------+
1 row in set (0.01 sec)

--  Query after the current date  12  Zhou 、5  Date of quarter 
/* select now(), date_add(now(),interval 12 week) date1, date_add(now(),interval 5 quarter) date2 from dual; */
mysql> select now(),
    ->        date_add(now(),interval 12 week) date1,
    ->        date_add(now(),interval 5 quarter) date2
    -> from dual;
+---------------------+---------------------+---------------------+
| now()               | date1               | date2               |
+---------------------+---------------------+---------------------+
| 2022-07-23 12:14:37 | 2022-10-15 12:14:37 | 2023-10-23 12:14:37 |
+---------------------+---------------------+---------------------+
1 row in set (0.00 sec)

--  After querying the current time  2  Hours 、125  minute 、258  The second time 
/* select now(), date_add(now(),interval 2 hour) time1, date_add(now(),interval 125 minute) time2, date_add(now(),interval 258 second) time3 from dual; */
mysql> select now(),
    ->        date_add(now(),interval 2 hour) time1,
    ->        date_add(now(),interval 125 minute) time2,
    ->        date_add(now(),interval 258 second) time3
    -> from dual;
+---------------------+---------------------+---------------------+---------------------+
| now()               | time1               | time2               | time3               |
+---------------------+---------------------+---------------------+---------------------+
| 2022-07-23 12:13:02 | 2022-07-23 14:13:02 | 2022-07-23 14:18:02 | 2022-07-23 12:17:20 |
+---------------------+---------------------+---------------------+---------------------+
1 row in set (0.00 sec)

（2） Inquire about 20 Students who celebrate their birthday days later

/* select * from student where month(birth) = date_add(now(),interval 20 day) and day(birth) = date_add(now(),interval 20 day); */
mysql> 
mysql> select * from student
    -> where month(birth) = date_add(now(),interval 20 day) and
    ->       day(birth) = date_add(now(),interval 20 day);
Empty set (0.01 sec)

2、ADDDATE() function

ADDDATE() Function and DATE_ADD() Functions are similar .

The syntax is as follows ：

ADDDATE(datetime,days)              -- increase  (n>0)  Or reduce  (n<0) n  God 
ADDDATE(datetime,interval n unit)   --  Usage and  DATE_ADD()  The function is exactly the same 

for example ：

mysql> select now(),adddate(now(),100),adddate(now(),-100) from dual;
+---------------------+---------------------+---------------------+
| now()               | adddate(now(),100)  | adddate(now(),-100) |
+---------------------+---------------------+---------------------+
| 2022-07-23 12:19:52 | 2022-10-31 12:19:52 | 2022-04-14 12:19:52 |
+---------------------+---------------------+---------------------+
1 row in set (0.00 sec)

3、DATEDIFF() function

Returns the number of days between two dates .

The syntax is as follows ：

--  Returns the number of days between two dates 
DATEDIFF(datetime1,datetime2)

for example ： Query the student's age

mysql> select s_id, s_name, birth, datediff(now(),birth)/365 age from student;
+-------+-----------+---------------------+---------+
| s_id  | s_name    | birth               | age     |
+-------+-----------+---------------------+---------+
| S2011 |  Zhang Xiaogang     | 1999-12-03 00:00:00 | 22.6521 |
| S2012 |  Liu Xiaoqing     | 1999-10-11 00:00:00 | 22.7973 |
| S2013 |  Cao mengde     | 1998-02-13 00:00:00 | 24.4548 |
| S2014 |  Liu Yan       | 1998-06-24 00:00:00 | 24.0959 |
| S2015 |  Liu Yan       | 1999-07-06 00:00:00 | 23.0630 |
| S2016 |  Liu Ruofei     | 2000-08-31 00:00:00 | 21.9068 |
| S2021 |  Dong Wenhua     | 2000-07-30 00:00:00 | 21.9945 |
| S2022 |  Zhou Huajian     | 1999-05-25 00:00:00 | 23.1781 |
| S2023 |  trump     | 1999-06-21 00:00:00 | 23.1041 |
| S2024 |  Obama     | 2000-10-17 00:00:00 | 21.7781 |
| S2025 |  Zhou Jianhua     | 2000-08-22 00:00:00 | 21.9315 |
| S2026 |  Zhang Xueyou     | 1998-07-06 00:00:00 | 24.0630 |
| S2031 |  Lee Myung Bak     | 1999-10-26 00:00:00 | 22.7562 |
| S2032 |  Vinci     | 1999-12-31 00:00:00 | 22.5753 |
+-------+-----------+---------------------+---------+
14 rows in set (0.00 sec)

4、TIMEDIFF() function

Returns the interval between two times .

The syntax is as follows ：

--  Returns the interval between two times 
TIMEDIFF(datetime1, datetime2)

for example ：

/* SET @time1 = '2022-7-23 18:23:15'; SET @time2 = '2022-7-22 18:23:15'; SET @time3 = '2022-5-29 18:23:15'; SELECT TIMEDIFF(NOW(),@time1),TIMEDIFF(NOW(),@time2),TIMEDIFF(NOW(),@time3) from dual; */
mysql> SET @time1 = '2022-7-23 18:23:15';
Query OK, 0 rows affected (0.01 sec)

mysql> SET @time2 = '2022-7-22 18:23:15';
Query OK, 0 rows affected (0.00 sec)

mysql> SET @time3 = '2022-5-29 18:23:15';
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT TIMEDIFF(NOW(),@time1),TIMEDIFF(NOW(),@time2),TIMEDIFF(NOW(),@time3)
    -> from dual;
+------------------------+------------------------+------------------------+
| TIMEDIFF(NOW(),@time1) | TIMEDIFF(NOW(),@time2) | TIMEDIFF(NOW(),@time3) |
+------------------------+------------------------+------------------------+
| 00:18:26               | 24:18:26               | 838:59:59              |
+------------------------+------------------------+------------------------+
1 row in set, 1 warning (0.00 sec)

5、 ... and 、 Other functions

1、DATE() and TIME() function

Returns the date and time in a date time expression .

The syntax is as follows ：

DATE(datetime)  --  Returns the date in the datetime expression 
TIME(datetime)  --  Returns the time in the date time expression 

for example ：

mysql> select now(),date(now()),time(now()) from dual;
+---------------------+-------------+-------------+
| now()               | date(now()) | time(now()) |
+---------------------+-------------+-------------+
| 2022-07-23 18:55:18 | 2022-07-23  | 18:55:18    |
+---------------------+-------------+-------------+
1 row in set (0.00 sec)

2、MAKEDATE() And MAKETIME() function

Generate the date and time according to the specified parameters .

The syntax is as follows ：

--  The first parameter represents the year , The second parameter represents the number of days 
--  The return value of the function indicates from the specified year  1  month  1  The day begins ,n  Days after 
MAKEDATE(year,n)
MAKETIME(hour,minute,second)   --  According to the parameters provided 、 branch 、 Seconds generate a time 

for example ：

mysql> select makedate(2022,152),makedate(2022,365),makedate(2022,455) from dual;
+--------------------+--------------------+--------------------+
| makedate(2022,152) | makedate(2022,365) | makedate(2022,455) |
+--------------------+--------------------+--------------------+
| 2022-06-01         | 2022-12-31         | 2023-03-31         |
+--------------------+--------------------+--------------------+
1 row in set (0.00 sec)

mysql> select maketime(22,15,33) from dual;
+--------------------+
| maketime(22,15,33) |
+--------------------+
| 22:15:33           |
+--------------------+
1 row in set (0.00 sec)

3、LAST_DAY() function

Returns the date of the last day of the month in which the date expression is located .

The syntax is as follows ：

LAST_DAY(datetime)

for example ：

mysql> select NOW(),LAST_DAY(NOW()),LAST_DAY('2022-2-5'),LAST_DAY('2020-2-5') 
       from dual\G
*************************** 1. row ***************************
               NOW(): 2022-07-23 19:06:33
     LAST_DAY(NOW()): 2022-07-31
LAST_DAY('2022-2-5'): 2022-02-28
LAST_DAY('2020-2-5'): 2020-02-29
1 row in set (0.00 sec)

4、DATE_FORMAT() function

Format a date .

The syntax is as follows ：

DATE_FORMAT(datetime, format)

/* --  according to  format  Display the date in the format specified by the string . -- format  The characters used in the string are as follows ： %a  The abbreviated name of a weekday  (Sun … Sat) %b  Abbreviated name of the month  (Jan … Dec) %c  month , Digital form (0 … 12) %D  Date of the month with English suffix  (0th, 1st, 2nd, 3rd, …) %d  Date of the month ,  Digital form  (00 … 31) %e  Date of the month ,  Digital form (0 … 31) %f  Microsecond  (000000 … 999999) %H  Hours (00 … 23) %h  Hours (01 … 12) %I  minute  (0 … 59) %i  minute , Digital form  (00 … 59) %j  Days of the year  (001 … 366) %k  Hours  (0 … 23) %l  Hours  (1 … 12) %M  The name of the month  (January … December) %m  month ,  Digital form  (00 … 12) %p  In the morning （AM） Or afternoon （ PM） %r  Time  , 12 hourly  ( Hours hh: minute mm: Number of seconds ss  After add  AM or PM) %S  second  (00 … 59) %s  second  (00 … 59) %T  Time ,24 hourly  ( Hours hh: minute mm: Number of seconds ss) %U  Zhou  (00 … 53),  Sunday is the first day of the week  %u  Zhou  (00 … 53),  Monday is the first day of the week  %V  Zhou  (01 … 53),  Sunday is the first day of the week  ;  and  %X Use at the same time  %v  Zhou  (01 … 53),  Monday is the first day of the week  ;  and  %x Use at the same time  %W  Weekday name  ( Sunday  …  Saturday ) %w  Every day of the week  (0= Sunday  … 6= Saturday ) %X  The year of the week , Sunday is the first day of the week ,  Digital form ,4 digit ; and %V Use at the same time  %x  The year of the week , Monday is the first day of the week ,  Digital form ,4 digit ; and %v Use at the same time  %Y  year ,  Digital form ,4 digit  %y  year ,  Digital form  (2 digit ) %% ‘%’ Characters  */

for example ：

（1） With 【M%D%,Y%】 Format display birth

mysql> select s_id, s_name, date_format(birth,'%M %d,%Y') birth from student;
+-------+-----------+------------------+
| s_id  | s_name    | birth            |
+-------+-----------+------------------+
| S2011 |  Zhang Xiaogang     | December 03,1999 |
| S2012 |  Liu Xiaoqing     | October 11,1999  |
| S2013 |  Cao mengde     | February 13,1998 |
| S2014 |  Liu Yan       | June 24,1998     |
| S2015 |  Liu Yan       | July 06,1999     |
| S2016 |  Liu Ruofei     | August 31,2000   |
| S2021 |  Dong Wenhua     | July 30,2000     |
| S2022 |  Zhou Huajian     | May 25,1999      |
| S2023 |  trump     | June 21,1999     |
| S2024 |  Obama     | October 17,2000  |
| S2025 |  Zhou Jianhua     | August 22,2000   |
| S2026 |  Zhang Xueyou     | July 06,1998     |
| S2031 |  Lee Myung Bak     | October 26,1999  |
| S2032 |  Vinci     | December 31,1999 |
+-------+-----------+------------------+
14 rows in set (0.00 sec)

（2） With 【%M %e,%Y】 Format display birth

mysql> select s_id, s_name, date_format(birth,'%M %e,%Y') birth from student;
+-------+-----------+------------------+
| s_id  | s_name    | birth            |
+-------+-----------+------------------+
| S2011 |  Zhang Xiaogang     | December 3,1999  |
| S2012 |  Liu Xiaoqing     | October 11,1999  |
| S2013 |  Cao mengde     | February 13,1998 |
| S2014 |  Liu Yan       | June 24,1998     |
| S2015 |  Liu Yan       | July 6,1999      |
| S2016 |  Liu Ruofei     | August 31,2000   |
| S2021 |  Dong Wenhua     | July 30,2000     |
| S2022 |  Zhou Huajian     | May 25,1999      |
| S2023 |  trump     | June 21,1999     |
| S2024 |  Obama     | October 17,2000  |
| S2025 |  Zhou Jianhua     | August 22,2000   |
| S2026 |  Zhang Xueyou     | July 6,1998      |
| S2031 |  Lee Myung Bak     | October 26,1999  |
| S2032 |  Vinci     | December 31,1999 |
+-------+-----------+------------------+
14 rows in set (0.00 sec)

（3） With 【%M %D,%Y】 Format display birth

mysql> select s_id, s_name, date_format(birth,'%M %D,%Y') birth from student;
+-------+-----------+--------------------+
| s_id  | s_name    | birth              |
+-------+-----------+--------------------+
| S2011 |  Zhang Xiaogang     | December 3rd,1999  |
| S2012 |  Liu Xiaoqing     | October 11th,1999  |
| S2013 |  Cao mengde     | February 13th,1998 |
| S2014 |  Liu Yan       | June 24th,1998     |
| S2015 |  Liu Yan       | July 6th,1999      |
| S2016 |  Liu Ruofei     | August 31st,2000   |
| S2021 |  Dong Wenhua     | July 30th,2000     |
| S2022 |  Zhou Huajian     | May 25th,1999      |
| S2023 |  trump     | June 21st,1999     |
| S2024 |  Obama     | October 17th,2000  |
| S2025 |  Zhou Jianhua     | August 22nd,2000   |
| S2026 |  Zhang Xueyou     | July 6th,1998      |
| S2031 |  Lee Myung Bak     | October 26th,1999  |
| S2032 |  Vinci     | December 31st,1999 |
+-------+-----------+--------------------+
14 rows in set (0.00 sec)

（4） With 【%a,%M %D,%Y】 The format shows the issue date of the stock

mysql> select s_id, s_name, date_format(birth,'%a, %M %D,%Y') birth from student;
+-------+-----------+-------------------------+
| s_id  | s_name    | birth                   |
+-------+-----------+-------------------------+
| S2011 |  Zhang Xiaogang     | Fri, December 3rd,1999  |
| S2012 |  Liu Xiaoqing     | Mon, October 11th,1999  |
| S2013 |  Cao mengde     | Fri, February 13th,1998 |
| S2014 |  Liu Yan       | Wed, June 24th,1998     |
| S2015 |  Liu Yan       | Tue, July 6th,1999      |
| S2016 |  Liu Ruofei     | Thu, August 31st,2000   |
| S2021 |  Dong Wenhua     | Sun, July 30th,2000     |
| S2022 |  Zhou Huajian     | Tue, May 25th,1999      |
| S2023 |  trump     | Mon, June 21st,1999     |
| S2024 |  Obama     | Tue, October 17th,2000  |
| S2025 |  Zhou Jianhua     | Tue, August 22nd,2000   |
| S2026 |  Zhang Xueyou     | Mon, July 6th,1998      |
| S2031 |  Lee Myung Bak     | Tue, October 26th,1999  |
| S2032 |  Vinci     | Fri, December 31st,1999 |
+-------+-----------+-------------------------+
14 rows in set (0.01 sec)