expression: fix cast invalid string to datetime

[wzru]

What problem does this PR solve?

Issue Number: close #24997

Problem Summary:

Simplified case:

drop table if exists t1, t2;
create table t1(c1 varbinary(100));
insert into t1 values('e');
create table t2(c1 date);
insert into t2 values('2019-11-10'); 
select * from t1 inner join t2 on t1.c1 <= t2.c1;

MySQL:

mysql> select * from t1 inner join t2 on t1.c1 <= t2.c1;
   
+------------+------------+
| c1         | c1         |
+------------+------------+
| 0x65       | 2019-11-10 |
+------------+------------+
1 row in set, 1 warning (0.00 sec)

TiDB:

mysql> select * from t1 inner join t2 on t1.c1 <= t2.c1;

Empty set, 1 warning (0.00 sec)

What is changed and how it works?

What's Changed:

func (b *builtinCastStringAsTimeSig) vecEvalTime
func (b *builtinCastStringAsTimeSig) evalTime

How it Works:

Check List

Tests

• Unit test
• Integration test

Side effects

• Performance regression: Consumes more CPU

Release note

None

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[wzru]

/cc @guo-shaoge @wshwsh12

[wshwsh12]

Please add some test cases for your modify.
For example.

MySQL [test]> select cast('e' as date);
+-------------------+
| cast('e' as date) |
+-------------------+
| NULL              |
+-------------------+

[XuHuaiyu]

@wzru
Any update for this PR?

[ti-chi-bot]

@wzru: PR needs rebase.

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[wshwsh12]

Should we use b.ctx.GetSessionVars().StrictSQLMode?

[hawkingrei]

@wzru Do you have time to finish this PR? If there is no reply within a week, I will close the PR and take over the job.

[wzru]

@hawkingrei Sorry for that. I don't have time yet. I will close this PR.

[hawkingrei]

@hawkingrei Sorry for that. I don't have time yet. I will close this PR.

Thank you for your contribution.