pingcap/tidb

zeroDate behavior for date_add and timestampdiff is not consistent in tidb

Open

#15,234 建立於 2020年3月9日

在 GitHub 查看
 (5 留言) (0 反應) (0 負責人)Go (40,090 star) (6,186 fork)batch import
component/expressionhelp wantedseverity/moderatesig/executiontype/bug

描述

Description

Bug Report

Please answer these questions before submitting your issue. Thanks!

  1. What did you do?
mysql> select timestampdiff(day,'0000-00-00 00:00:00','2020-01-01 00:00:00');
+----------------------------------------------------------------+
| timestampdiff(day,'0000-00-00 00:00:00','2020-01-01 00:00:00') |
+----------------------------------------------------------------+
|                                                           NULL |
+----------------------------------------------------------------+
1 row in set, 1 warning (0.00 sec)

mysql> select date_add('0000-00-00 00:00:00', interval 2020 year);
+-----------------------------------------------------+
| date_add('0000-00-00 00:00:00', interval 2020 year) |
+-----------------------------------------------------+
| 2019-11-30 00:00:00                                 |
+-----------------------------------------------------+
1 row in set, 1 warning (0.00 sec)

  1. What did you expect to see? timestampdiff and date_add should both return NULL or meaningful result. BTW in mysql both timestampdiff and date_add return NULL

  2. What did you see instead?

mysql> select timestampdiff(day,'0000-00-00 00:00:00','2020-01-01 00:00:00');
+----------------------------------------------------------------+
| timestampdiff(day,'0000-00-00 00:00:00','2020-01-01 00:00:00') |
+----------------------------------------------------------------+
|                                                           NULL |
+----------------------------------------------------------------+
1 row in set, 1 warning (0.00 sec)

mysql> select date_add('0000-00-00 00:00:00', interval 2020 year);
+-----------------------------------------------------+
| date_add('0000-00-00 00:00:00', interval 2020 year) |
+-----------------------------------------------------+
| 2019-11-30 00:00:00                                 |
+-----------------------------------------------------+
1 row in set, 1 warning (0.00 sec)
  1. What version of TiDB are you using (tidb-server -V or run select tidb_version(); on TiDB)?

tidb master

貢獻者指南

技術棧
gomysql
領域
backenddatabase
議題類型
bug
難度面向新貢獻者的預計實作難度，1 表示很小改動，5 表示專家級工作。
3
預計時間有經驗貢獻者完成調查、實作、測試並準備 pull request 的粗略時間範圍。
half day
活動狀態議題目前的可參與程度：新鮮、活躍、陳舊、阻塞或等待維護者輸入。
stale
清晰度議題是否清楚說明預期改動、驗收標準和下一步。
clear
前置要求
Go programmingTiDB source code navigationMySQL SQL syntax
新手友善度1-100 的估計分數，表示該議題對首次貢獻者的友善程度。
65
研究方向
Look for the implementation of 'date add' and 'timestampdiff' functions in the TiDB source code, likely under the 'expression' or 'time' package. Check how zero dates (0000-00-00) are handled. The expected behavior is to return NULL for invalid dates, as MySQL does. Compare with MySQL's handling. The fix should ensure consistent NULL return for zero dates in both functions.