Karlos Karlos - 1 month ago 8
MySQL Question

Error in mysql when setting default value for DATE or DATETIME

I'm running MySql Server 5.7.11 and this sentence:

updated datetime NOT NULL DEFAULT '0000-00-00 00:00:00'


is not working. Giving the error:

ERROR 1067 (42000): Invalid default value for 'updated'


But the following:

updated datetime NOT NULL DEFAULT '1000-01-01 00:00:00'


just works.

The same case for DATE.

As a sidenote, it is mentioned in the mysql docs:


The DATE type is used for values with a date part but no time part. MySQL retrieves and displays DATE values in 'YYYY-MM-DD' format. The supported range is '1000-01-01' to '9999-12-31'.


even if they also say:


Invalid DATE, DATETIME, or TIMESTAMP values are converted to the “zero” value of the appropriate type ('0000-00-00' or '0000-00-00 00:00:00').


Having also into account the second quote from mysql documentation, could anyone let me know why it is giving that error?

Answer

The error is because of the sql mode which can be strict mode as per latest MYSQL 5.7 documentation

MySQL Documentation 5.7 says:

Strict mode affects whether the server permits '0000-00-00' as a valid date: If strict mode is not enabled, '0000-00-00' is permitted and inserts produce no warning. If strict mode is enabled, '0000-00-00' is not permitted and inserts produce an error, unless IGNORE is given as well. For INSERT IGNORE and UPDATE IGNORE, '0000-00-00' is permitted and inserts produce a warning.

To Check MYSQL mode

SELECT @@GLOBAL.sql_mode global, @@SESSION.sql_mode session

Disabling STRICT_TRANS_TABLES mode

However to allow the format 0000-00-00 00:00:00you have to disable STRICT_TRANS_TABLES mode in mysql config file or by command

By command

SET sql_mode = '';

if above is not working than go to /etc/mysql/my.cnf (as per ubuntu) and comment out STRICT_TRANS_TABLES

Note

However strict mode is not enabled by default in MYSQL 5.6. Hence it does not produce the error as per MYSQL 6 documentation which says

MySQL permits you to store a “zero” value of '0000-00-00' as a “dummy date.” This is in some cases more convenient than using NULL values, and uses less data and index space. To disallow '0000-00-00', enable the NO_ZERO_DATE SQL mode.

UPDATE

Regarding the bug matter as said by @Dylan-Su:

I don't think this is the bug it the way MYSQL is evolved over the time due to which some things are changed based on further improvement of the product.

However I have another related bug report regarding the NOW() function

Datetime field does not accept default NOW()

Another Useful note [see Automatic Initialization and Updating for TIMESTAMP and DATETIME]

As of MySQL 5.6.5, TIMESTAMP and DATETIME columns can be automatically initializated and updated to the current date and time (that is, the current timestamp). Before 5.6.5, this is true only for TIMESTAMP, and for at most one TIMESTAMP column per table. The following notes first describe automatic initialization and updating for MySQL 5.6.5 and up, then the differences for versions preceding 5.6.5.

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