Original address: https://www.cnblogs.com/mxh1099/p/5461311.html
1. TIMESTAMP[(M)]
timestamp. The range is '1970-01-01 00:00:00' to 2037.
TIMESTAMP columns are used to record the date and time during INSERT or UPDATE operations.
If you don't assign a value, the first TIMESTAMP column in the table is automatically set to the date and time of the most recent operation.
It is also possible to set a TIMESTAMP column to the current date and time by assigning a NULL value.
After the TIMESTAMP value is returned, it is displayed as a string in the format of 'YYYY-MM-DD HH:MM:SS', and the
display width is fixed to 19 characters. If you want to get a numeric value, you should add +0 to the TIMESTAMP column.
create table demo(
addtime timestamp
);
insert into demo values(null);
to insert the current time.
2. TIME
time. The range is '-838:59:59' to '838:59:59'.
MySQL displays TIME values in the 'HH:MM:SS' format, but allows strings or numbers to be used to assign values to TIME columns.
Use now() to display 'HH:MM:SS'
Use UNIX_TIMESTAMP() to display '-838:59:59' to '838:59:59'.
mysql> insert into pluralpoem(title, create_time) values("chunxiao", UNIX_TIMESTAMP());
Query OK, 1 row affected, 1 warning (0.01 sec)
mysql> insert into pluralpoem(title, create_time) values("hua",now());
Query OK, 1 row affected (0.00 sec)
mysql> select * from pluralpoem;
+----+------------+-------------+
| id | title | create_time |
+----+------------+-------------+
| 1 | denggaowan | NULL |
| 2 | chunxiao | 838:59:59 |
| 3 | hua | 22:45:33 |
+----+------------+-------------+
3 rows in set (0.00 sec)
Three, DATETIME
date and time combination.
The supported range is '1000-01-01 00:00:00' to '9999-12-31 23:59:59'.
MySQL displays DATETIME values in the 'YYYY-MM-DD HH:MM:SS' format, but allows strings or numbers to be used to assign values to DATETIME columns.
4. For now()., curdate(), curtime(), UNIX_TIMESTAMP()
The NOW() function returns the current date and time as `'YYYY-MM-DD HH:MM:SS', which can be directly stored in the DATETIME field.
CURDATE() returns today's date in the format 'YYYY-MM-DD', which can be directly stored in the DATE field.
CURTIME() returns the current time in the format of 'HH:MM:SS', which can be directly stored in the TIME field.
UNIX_TIMESTAMP()