[mysql] Why there can be only one TIMESTAMP column with CURRENT_TIMESTAMP in DEFAULT clause?

Why there can be only one TIMESTAMP column with CURRENT_TIMESTAMP in DEFAULT or ON UPDATE clause?

CREATE TABLE `foo` (
  `ProductID` INT(10) UNSIGNED NOT NULL,
  `AddedDate` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `UpdatedDate` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
) ENGINE=INNODB;

The error that results:

Error Code : 1293

Incorrect table definition; there can be only one TIMESTAMP column with CURRENT_TIMESTAMP in DEFAULT or ON UPDATE clause

We can give a default value for the timestamp to avoid this problem.

This post gives a detailed workaround: http://gusiev.com/2009/04/update-and-create-timestamps-with-mysql/

create table test_table( 
id integer not null auto_increment primary key, 
stamp_created timestamp default '0000-00-00 00:00:00', 
stamp_updated timestamp default now() on update now() 
);

Note that it is necessary to enter nulls into both columns during "insert":

mysql> insert into test_table(stamp_created, stamp_updated) values(null, null); 
Query OK, 1 row affected (0.06 sec)
mysql> select * from t5; 
+----+---------------------+---------------------+ 
| id | stamp_created       | stamp_updated       |
+----+---------------------+---------------------+
|  2 | 2009-04-30 09:44:35 | 2009-04-30 09:44:35 |
+----+---------------------+---------------------+
2 rows in set (0.00 sec)  
mysql> update test_table set id = 3 where id = 2; 
Query OK, 1 row affected (0.05 sec) Rows matched: 1  Changed: 1  Warnings: 0  
mysql> select * from test_table;
+----+---------------------+---------------------+
| id | stamp_created       | stamp_updated       | 
+----+---------------------+---------------------+ 
|  3 | 2009-04-30 09:44:35 | 2009-04-30 09:46:59 | 
+----+---------------------+---------------------+ 
2 rows in set (0.00 sec) 

Indeed an implementation fault.

The native approach in MySQL is to update a creation date yourself ( if you need one ) and have MySQL worry about the timestamp update date ? update date : creation date like so:

CREATE TABLE tracked_data( 
  `data` TEXT,
  `timestamp`   TIMESTAMP,
  `creation_date` TIMESTAMP                                   
) ENGINE=INNODB; 

On creation Insert NULL:

INSERT INTO tracked_data(`data`,`creation_date`) VALUES ('creation..',NULL);

NULL values for timestamp are interperted as CURRENT_TIMESTAMP by default.

In MySQL the first TIMESTAMP column of a table gets both DEFAULT CURRENT_TIMESTAMP and ON UPDATE CURRENT_TIMESTAMP attribute, if no attributes are given for it. this is why TIMESTAMP column with attributes must come first or you get the error described in this thread.

Combining various answers :

In MySQL 5.5, DEFAULT CURRENT_TIMESTAMP and ON UPDATE CURRENT_TIMESTAMP cannot be added on DATETIME but only on TIMESTAMP.

Rules:

1) at most one TIMESTAMP column per table could be automatically (or manually[My addition]) initialized or updated to the current date and time. (MySQL Docs).

So only one TIMESTAMP can have CURRENT_TIMESTAMP in DEFAULT or ON UPDATE clause

2) The first NOT NULL TIMESTAMP column without an explicit DEFAULT value like created_date timestamp default '0000-00-00 00:00:00' will be implicitly given a DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP and hence subsequent TIMESTAMP columns cannot be given CURRENT_TIMESTAMP on DEFAULT or ON UPDATE clause

CREATE TABLE `address` (
  `id` int(9) NOT NULL AUTO_INCREMENT,
  `village` int(11) DEFAULT NULL,
    `created_date` timestamp default '0000-00-00 00:00:00', 

    -- Since explicit DEFAULT value that is not CURRENT_TIMESTAMP is assigned for a NOT NULL column, 
    -- implicit DEFAULT CURRENT_TIMESTAMP is avoided.
    -- So it allows us to set ON UPDATE CURRENT_TIMESTAMP on 'updated_date' column.
    -- How does setting DEFAULT to '0000-00-00 00:00:00' instead of CURRENT_TIMESTAMP help? 
    -- It is just a temporary value.
    -- On INSERT of explicit NULL into the column inserts current timestamp.

-- `created_date` timestamp not null default '0000-00-00 00:00:00', // same as above

-- `created_date` timestamp null default '0000-00-00 00:00:00', 
-- inserting 'null' explicitly in INSERT statement inserts null (Ignoring the column inserts the default value)! 
-- Remember we need current timestamp on insert of 'null'. So this won't work. 

-- `created_date` timestamp null , // always inserts null. Equally useless as above. 

-- `created_date` timestamp default 0, // alternative to '0000-00-00 00:00:00'

-- `created_date` timestamp, 
-- first 'not null' timestamp column without 'default' value. 
-- So implicitly adds DEFAULT CURRENT_TIMESTAMP and ON UPDATE CURRENT_TIMESTAMP. 
-- Hence cannot add 'ON UPDATE CURRENT_TIMESTAMP' on 'updated_date' column.


   `updated_date` timestamp null on update current_timestamp,

  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=132 DEFAULT CHARSET=utf8;

INSERT INTO address (village,created_date) VALUES (100,null);

mysql> select * from address;
+-----+---------+---------------------+--------------+
| id  | village | created_date        | updated_date |
+-----+---------+---------------------+--------------+
| 132 |     100 | 2017-02-18 04:04:00 | NULL         |
+-----+---------+---------------------+--------------+
1 row in set (0.00 sec)

UPDATE address SET village=101 WHERE village=100;

mysql> select * from address;
+-----+---------+---------------------+---------------------+
| id  | village | created_date        | updated_date        |
+-----+---------+---------------------+---------------------+
| 132 |     101 | 2017-02-18 04:04:00 | 2017-02-18 04:06:14 |
+-----+---------+---------------------+---------------------+
1 row in set (0.00 sec)

Other option (But updated_date is the first column):

CREATE TABLE `address` (
  `id` int(9) NOT NULL AUTO_INCREMENT,
  `village` int(11) DEFAULT NULL,
  `updated_date` timestamp null on update current_timestamp,
  `created_date` timestamp not null , 
  -- implicit default is '0000-00-00 00:00:00' from 2nd timestamp onwards

  -- `created_date` timestamp not null default '0000-00-00 00:00:00'
  -- `created_date` timestamp
  -- `created_date` timestamp default '0000-00-00 00:00:00'
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=132 DEFAULT CHARSET=utf8;

This is the limitation in MYSQL 5.5 version. You need to update the version to 5.6.

Error

I was getting this error in adding a table in MYSQL

Incorrect table definition; there can be only one TIMESTAMP column with CURRENT_TIMESTAMP in DEFAULT or ON UPDATE clause My new MYSQL

table looks something like this.

create table table_name (col1 int(5) auto_increment primary key, col2 varchar(300), col3 varchar(500), col4 int(3), col5 tinyint(2), col6 timestamp default current_timestamp, col7 timestamp default current_timestamp on update current_timestamp, col8 tinyint(1) default 0, col9 tinyint(1) default 1);

After some time of reading about changes in different MYSQL versions and some of the googling. I found out that there was some changes that were made in MYSQL version 5.6 over version 5.5.

This article will help you to resolve the issue. http://www.oyewiki.com/MYSQL/Incorrect-table-definition-there-can-be-only-one-timestamp-column

I also wondered that long time ago. I searched a bit in my history and I think that this post: http://lists.mysql.com/internals/34919 represents the semi-official position of MySQL (before Oracle's intervention ;))

In short:

this limitation stems only from the way in which this feature is currently implemented in the server and there are no other reasons for its existence.

So their explanation is "because it is implemented like this". Doesn't sound very scientific. I guess it all comes from some old code. This is suggested in the thread above: "carry-over from when only the first timestamp field was auto-set/update".

Cheers!

Well a fix for you could be to put it on the UpdatedDate field and have a trigger that updates the AddedDate field with the UpdatedDate value only if AddedDate is null.

1. Change data types of columns to datetime
2. Set trigger

Such as:

DROP TRIGGER IF EXISTS `update_tablename_trigger`;
DELIMITER //
CREATE TRIGGER `update_tablename_trigger` BEFORE UPDATE ON `tablename`
 FOR EACH ROW SET NEW.`column_name` = NOW()
//
DELIMITER ;

Try this:

CREATE TABLE `test_table` (
`id` INT( 10 ) NOT NULL,
`created_at` TIMESTAMP NOT NULL DEFAULT 0,
`updated_at` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
) ENGINE = INNODB;