Bug: ON UPDATE CURRENT_TIMESTAMP is missing after table creation

Reproduction on build 9.1.0.4888:

CREATE TABLE `test` (
`field` TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
);

Now open the table and view the "CREATE code" tab. The ON UPDATE CURRENT_TIMESTAMP part is missing. However, a DEFAULT of CURRENT_TIMESTAMP is shown correctly.

The ON UPDATE clause is not implicitly set by MySQL, so the CREATE code is invalid.

Problem is HeidiSQL expecting some "DEFAULT CURRENT_TIMESTAMP ...", where MySQL silently modified your original code to this one:

CREATE TABLE `test` (
`field` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00' ON UPDATE CURRENT_TIMESTAMP
) ENGINE=MyISAM DEFAULT CHARSET=latin1

The right way would be HeidiSQL displays it this way:

If I use your example CREATE SQL, I still get the wrong default value (CURRENT_TIMESTAMP instead of '0000-00-00 00:00:00'):



So we agree this is a bug, right? :)

To explain a bit more:

* MySQL interprets the first DEFAULT CURRENT_TIMESTAMP column implicitly as a ON UPDATE CURRENT_TIMESTAMP column.
* The default value for a column is separate from the ON UPDATE clause.

So when interpreting the SHOW CREATE TABLE output, you can actually trust the DEFAULT and ON UPDATE values as separate, valid values. The ON UPDATE value in HeidiSQL should never be dependent on the DEFAULT value!

Yes, of course, we agree about a bug hereI was explaining the bug cause more to myself, so I can reproduce and fix it.

Should be fixed in r4893