ddl: disallow change columns from zero int to time

[tangenta]

What problem does this PR solve?

Issue Number: close #25285

Problem Summary:

MySQL does not allow conversion from zero integers to time during column type change.

What is changed and how it works?

What's Changed: Add a zero-check in ParseTimeFromNum.

Related changes

NA

Check List

Tests

• Unit test
• Integration test

Side effects

NA

Release note

• disallow change columns from zero integers to time.

[tangenta]

Updated. I did some experiments on MySQL 8.0 and recorded some behaviors: #25285 (comment).

After this PR, there remains only one incompatibility:

set @@sql_mode='no_zero_date';
select timestamp(0);

In MySQL 8.0 we get NULL but in TiDB we get 0000-00-00 00:00:00. To make it compatible, we need to change some fields in StmtContext.

Since this is another issue, let's do the work in the next PR.

[zimulala]

LGTM

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• djshow832
• zimulala

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

The full list of commands accepted by this bot can be found here.

Reviewer can indicate their review by submitting an approval review.
Reviewer can cancel approval by submitting a request changes review.

[AilinKid]

Rest LGTM

[AilinKid]

might we add a brief comment here (cast diff in select & alter)

[bb7133]

@tangenta Please update the comment according to the address, thanks.

[djshow832]

I'm afraid it's another compatibility breaker, which may hurt our previous users. Have you discussed it with others?

[tangenta]

I'm afraid it's another compatibility breaker, which may hurt our previous users. Have you discussed it with others?

To keep the same behavior as the previous version, the users can remove the 'strict' mode.

[tisonkun]

I'm afraid it's another compatibility breaker, which may hurt our previous users. Have you discussed it with others?

To keep the same behavior as the previous version, the users can remove the 'strict' mode.

@djshow832 is this an acceptable answer to you? I don't know whether it is a requirement to change other things at a whole. If so, it is not a resolution to me because users want to keep the original behavior cannot achieve it without other potential risks.

[djshow832]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 189c08f

[ti-chi-bot]

@tangenta: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.