TYPO3 Core

Steps to reproduce:

1. Have MySQL in strict mode (i.e., the default configuration without any changes): STRICT_TRANS_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION (this is MariaDB's default)
1. Have an extension with a date or datetime field that uses the config 'eval' => 'date' or 'eval' => 'datetime'
1. Fill in a date and save.
1. Empty the date (by using the "clear" icon) and save again.

Expected result:
The date field is emptied, and there is no error message.

Actual result:
The date field still has the date value (that should have been removed), and an error flash message is displayed:

SQL error: 'Incorrect integer value: " for column `…'

Additional information:

Bug report in the seminars extension:
https://github.com/oliverklee/ext-seminars/issues/548

Workaround in the seminars extension:
Add an int eval: https://github.com/oliverklee/ext-seminars/pull/549/files

So empty date and datetime fields need to be cast to an integer before saving so that an empty value gets converted to 0.