Various time functions of Mysql _ MySQL

Various Mysql time functions bitsCN.com

Various time functions of Mysql

Mysql has rich time functions.

1. filtering condition in mysql Query time where the second is not 0

SQL code

SECOND (t. file_time)

2. current time

SQL code

Now ()

3. one day ago

SQL code

Select DATE_SUB (curdate (), INTERVAL 1 DAY)

4. default value of timestamp

Weird problem with mysql timestamp field

Table creation statement:

SQL code

Create table 'testtimestamp '(

'Id' int not null AUTO_INCREMENT,

'File _ time' timestamp not null,

'Scan _ time' timestamp null,

'Created 'timestamp not null,

'Modified' timestamp not null,

Primary key ('id ')

) ENGINE = InnoDB AUTO_INCREMENT = 1 default charset = utf8;

After Execution, the default value of file_time is CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP.

The default value of scan_time is NULL.

The default values of created and modified are '2017-00-00 00:00:00'

The first timestamp field of the statement to be created is CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP.

In addition, when file_time is updated, if it is not in the set group, the default value is now ()!!!???

This will lead to a default value. if this field is not found in the update statement, the current time will be filled by default.

Modify type:

SQL code

Alter table 'database'. 'tablename' change column 'columname' timestamp not null default '2017-00-00 00:00:00 ';

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