MySQL 時(shí)間函數(shù)

A. timestampdiff() 傳三個(gè)參數(shù)，第一個(gè)時(shí)間類型如年，月，日，第二個(gè)開(kāi)始時(shí)間，第三個(gè)結(jié)束時(shí)間
select test_name, timestampdiff(YEAR,create_time,end_time) y_date from test_table; --計(jì)算時(shí)間

+-----------+--------+
| test_name | y_date |
+-----------+--------+
| 哈羅德 | 29 |
| 哈羅德 | 17 |
| 格溫 | 13 |
| 班尼 | 110 |
+-----------+--------+

B. INTERVAL n day day還可以替換為年月等
select now()+ INTERVAL 1 day; --表示明天

+-----------------------+
| now()+ INTERVAL 1 day |
+-----------------------+
| 2018-12-07 09:52:03 |
+-----------------------+

C. last_day() 括號(hào)內(nèi)加個(gè)時(shí)間日期，表示月末
select last_day(now()); --表示月末

+-----------------+
| last_day(now()) |
+-----------------+
| 2018-12-31 |
+-----------------+

D. extract(day from now()) 表示某月第幾天，day 還可以替換為year,month 等
select date_sub(date(now()),interval extract(day from now()) - 1 day) as 'month_firstday'; 月初

+----------------+
| month_firstday |
+----------------+
| 2018-12-01 |
+----------------+

E. date_format() 把一個(gè)日期/時(shí)間轉(zhuǎn)換成各種各樣的字符串格式

select date_format(now(),'%Y-%m-%d %h:%i:%s'); %Y：年，% m:月， %M：英文月，%d: 日， %D ：英文日， %h:小時(shí)，%H:24小時(shí)制，%i:分鐘，%s:秒

+----------------------------------------+
| date_format(now(),'%Y-%m-%d %h:%i:%s') |
+----------------------------------------+
| 2018-12-06 10:28:04 |
+----------------------------------------+

F. str_to_date() 把一個(gè)字符串格式日期/時(shí)間轉(zhuǎn)換成時(shí)間
select str_to_date('07.10.2017 08:09:30', '%m.%d.%Y %h:%i:%s') as st_to_d;

+---------------------+
| st_to_d |
+---------------------+
| 2017-07-10 08:09:30 |
+---------------------+
1 row in set (0.06 sec)

G. date_add(),date_sub()
select date_add(now(), interval 1 day) as add_day; 加一天， 表示明天

+---------------------+
| add_day |
+---------------------+
| 2018-12-07 10:46:50 |
+---------------------+
1 row in set (0.00 sec)

select date_add(now(), interval 1 day) as add_day; 減一天，表示昨天

+---------------------+
| sub_day |
+---------------------+
| 2018-12-05 10:48:48 |
+---------------------+
1 row in set (0.00 sec)

H. select week(now()); 年中第幾周
select quarter(now()); 季度
select dayofweek(now()); 一周中第幾天
select dayofmonth(now()); 一個(gè)月第幾天
select dayofyear(now()); 一年第幾天
show variables like 'lc_time_names';
select dayname(now()),monthname(now()); 英文周幾，英文月份

+----------------+------------------+
| dayname(now()) | monthname(now()) |
+----------------+------------------+
| Thursday | December |
+----------------+------------------+

set lc_time_names='zh_CN'; 時(shí)間名稱改為中文

+----------------+------------------+
| dayname(now()) | monthname(now()) |
+----------------+------------------+
| 星期四 | 十二月 |
+----------------+------------------+