Different results of time() · pingcap/tidb#11866

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Description

Bug Report

Please answer these questions before submitting your issue. Thanks!

What did you do? If possible, provide a recipe for reproducing the error.

select time("10:11:1212");
select time("-1? 10:11:12");

Need to refine ParseDuration in types/time.go

What did you expect to see?

mysql> select time("10:11:1212");
+--------------------+
| time("10:11:1212") |
+--------------------+
| NULL               |
+--------------------+
1 row in set, 1 warning (0.00 sec)

mysql> select time("-1? 10:11:12");
+----------------------+
| time("-1? 10:11:12") |
+----------------------+
| -00:00:01            |
+----------------------+
1 row in set, 1 warning (0.00 sec)

Note: according to https://dev.mysql.com/doc/refman/5.7/en/time.html The first result should be 00:00:00 insteal of NULL 3. What did you see instead?

mysql> select time("10:11:1212");
+--------------------+
| time("10:11:1212") |
+--------------------+
| 10:11:12           |
+--------------------+
1 row in set (0.00 sec)

mysql> select time("-1? 10:11:12");
+----------------------+
| time("-1? 10:11:12") |
+----------------------+
| -10:11:12            |
+----------------------+
1 row in set (0.00 sec)

What version of TiDB are you using (tidb-server -V or run select tidb_version(); on TiDB)?

mysql> select tidb_version();
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tidb_version()                                                                                                                                                                                                                                                                                                                  |
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Release Version: v4.0.0-alpha-119-ge8597cd03
Git Commit Hash: e8597cd0398e9ef3fc71803271270c179cd1fb7d
Git Branch: fix_time
UTC Build Time: 2019-08-26 05:04:46
GoVersion: go version go1.12.4 linux/amd64
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false |
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

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Score

Mentor

@qw4990

Contributor guide

Tech stack: gosql
Domain: backenddatabase
Issue type: bug
Difficulty: 3
Estimated time: under 1 hour
Activity status: stale
Clarity: clear
Prerequisites: Go programmingtime parsingMySQL compatibility
Newbie friendliness: 70
Research direction: Examine the ParseDuration function in types/time.go. Understand the current behavior and compare with MySQL's time parsing as per documentation. Focus on handling invalid time strings like '10:11:1212' where extra digits should result in NULL, and negative signs with invalid characters like ' 1? 10:11:12'. The fix should adjust the parsing logic to match MySQL's behavior. Consult the mentor @qw4990 for guidance.