planner: Fix Empty string has different meanings in SELECT and UPDATE

[yuqi1129]

What problem does this PR solve?

Issue Number: close #27648

Problem Summary:

What is changed and how it works?

Proposal: xxx

What's Changed:

How it Works:

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

None

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[yuqi1129]

/cc @xiongjiwei @lzmhhh123

[time-and-fate]

Thanks for your contribution!

[ti-chi-bot]

@yuqi1129: PR needs rebase.

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[xiongjiwei]

seems has been fixed by #28229

[yuqi1129]

@xiongjiwei , As you have commented, #28229 issue have introduced a new problem, maybe we should consider this two issue both and come up with a solution.

[winoros]

Seems the EvalBool behavior is not the same with MySQL

mysql> /* s1 */ select * from t where ' ';
Empty set, 1 warning (0.00 sec)

mysql> show warnings;
+---------+------+--------------------------------------+
| Level   | Code | Message                              |
+---------+------+--------------------------------------+
| Warning | 1292 | Truncated incorrect DOUBLE value: '' |
+---------+------+--------------------------------------+
1 row in set (0.01 sec)

mysql> /* s1 */ select * from t where ' ';
Empty set (0.00 sec)

The first one is the TiDB's. You can see that MySQL doesn't throw warning out.
This could be a problem if we use a strict SQL mode. MySQL would success and TiDB would fail

[yudongusa]

@yuqi1129 @xiongjiwei @winoros any update on this issue?