MySQL create time and update time timestamp

问题

I am creating some tables where I want to store the time when a record was created and when it was last updated. I thought I could have two timestamp fields where one would have the value CURRENT_TIMESTAMP and the other would have CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP. But I guess I can't do this because you can have only 1 timestamp field with a default value in a table?

How would you recommend I get and store the two times? Thanks!

回答1:

You can have two columns of type timestamp in one table.

The following works for MySQL 5.0

create table t 
(
  id integer, 
  created_at timestamp default current_timestamp, 
  updated_at timestamp
);

I think you are confusing this with SQL Server (where timestamp is not really a "time stamp" and there is indeed a limit on a single "timestamp" column)

Edit: But you will need a trigger to update the update_at column each time the row is changed.

回答2:

A good way to create fields like 'created' and 'updated' is

CREATE TABLE `mytable` ( 
`id` INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY, 
`created` TIMESTAMP DEFAULT '0000-00-00 00:00:00', 
`updated` TIMESTAMP DEFAULT now() ON UPDATE now(),
`myfield` VARCHAR(255)
);

And its necessary to enter nulls into both columns during "insert":

INSERT INTO mytable (created,updated,myfield) VALUES (null,null,'blablabla');

And now, in all updates, the 'updated' field will have a new value with actual date.

UPDATE mytable SET myfield='blablablablu' WHERE myfield='blablabla';

Source : http://gusiev.com/2009/04/update-and-create-timestamps-with-mysql/

回答3:

As of MYSQL version 5.6.5 you can do this using DEFAULT and ON UPDATE. No triggers are needed.

ts_create TIMESTAMP DEFAULT CURRENT_TIMESTAMP,

ts_update TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP

回答4:

As far as I know, there's no workaround for that restriction. You'll need to manually set (at least) one of the timestamps, the easiest way is just add updated = NOW() to the UPDATE-query.

回答5:

You'll need two columns: CREATE_TIME and UPDATE_TIME.

You might want to add CREATE_USER and UPDATE_USER.

Perhaps you'd want to have a 1:many relationship with name of column changed, old and new values.

It's all part of change data capture. You could have CDC tables that are updated using triggers.

回答6:

I would leave the current timestamp the way you suggested and fill in the created_at field with current date on insert.

来源：https://stackoverflow.com/questions/3488536/mysql-create-time-and-update-time-timestamp

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