如何执行 SQL 在表的新列中插入时间戳并转换为数据类型 DATETIME

Question

我有一个数据类型为 VARCHAR 的列“TIMESTAMP”的表：

CREATE TABLE Table1
    (`ID` int, `TIMESTAMP` varchar(24), `TOPIC` varchar(30), `PAYLOAD` numeric, `UNIT` varchar(5), `SENSOR` varchar(25), `DerivedValue` int, `DerivedValueDesc` varchar(17))
;
    
INSERT INTO Table1
    (`ID`, `TIMESTAMP`, `TOPIC`, `PAYLOAD`, `UNIT`, `SENSOR`, `DerivedValue`, `DerivedValueDesc`)
VALUES
    (17463, '2019-11-28T17:58:12.776Z', 'Wago-855-9150', 475.29334, 'W', '"Wago 855-9150/2000-0701"', 1, '"Produktion ja"'),
    (17464, '2019-11-28T17:58:13.675Z', 'ifm-O5D150', 19.0625, 'cm', '"ifm O5D150"', 1, '"Tür offen"'),
    (17465, '2019-11-28T17:58:13.675Z', 'Keyence-FD-Q20C', 0, 'L/min', '"Keyence FD-Q20C"', 0, '"Durchfluss nein"'),
    (17466, '2019-11-28T17:58:14.676Z', 'ifm-O5D150', 23.0625, 'cm', '"ifm O5D150"', 0, '"Tür zu"'),
    (17467, '2019-11-28T17:58:14.676Z', 'Keyence-FD-Q20C', 0, 'L/min', '"Keyence FD-Q20C"', 0, '"Durchfluss nein"'),
    (17468, '2019-11-28T17:58:14.776Z', 'Wago-855-9150', 569.14666, 'W', '"Wago 855-9150/2000-0701"', 1, '"Produktion ja"')
;

现在发现查询表非常耗时：

SELECT PAYLOAD FROM Table1 WHERE TOPIC LIKE '%temperature%' AND CAST(TIMESTAMP AS datetime) between '2019-09-29 00:00:00' and '2019-09-29 00:59:59';

所以我们的想法是创建一个额外的列并将时间戳存储在数据类型 DATETIME 中：

ALTER TABLE Table1 ADD `DATETIME` DATETIME AFTER `TIMESTAMP`; 

然后我想用来自 TIMESTAMP 列的转换数据填充新列：

INSERT INTO Table1(DATETIME) SELECT CAST(`TIMESTAMP` AS DATETIME) FROM Table1;

然后我收到错误消息：

错误：ER_TRUNCATED_WRONG_VALUE：截断不正确的日期时间值：'2019-11-28T17:58:12.776Z'

在https://www.db-fiddle.com/和http://sqlfiddle.com/中对查询进行原型设计时出现此错误。 我正在使用 MySQL 数据库 v5.7。

有趣的是，这个查询有效：

SELECT `TIMESTAMP`, CAST(`TIMESTAMP` AS DATETIME) AS `MYDATETIME` FROM Table1;

但我需要新列中的数据而不是查询中的数据。

我的错误是什么？ 我认为最好不要采用像 STR_TO_DATE 这样的字符串操作，因为对秒数的取整会产生不确定的后果。

Answer 1

唯一不同意 MySQL 日期文字格式的部分是末尾的'Z' 。

mysql> select cast('2019-11-28T17:58:12.776Z' as datetime);
+----------------------------------------------+
| cast('2019-11-28T17:58:12.776Z' as datetime) |
+----------------------------------------------+
| 2019-11-28 17:58:13                          |
+----------------------------------------------+
1 row in set, 1 warning (0.00 sec)

Warning (Code 1292): Truncated incorrect datetime value: '2019-11-28T17:58:12.776Z'

但是修剪'Z'就可以了：

mysql> select cast(trim(trailing 'Z' from '2019-11-28T17:58:12.776Z') as datetime);
+----------------------------------------------------------------------+
| cast(trim(trailing 'Z' from '2019-11-28T17:58:12.776Z') as datetime) |
+----------------------------------------------------------------------+
| 2019-11-28 17:58:13                                                  |
+----------------------------------------------------------------------+
1 row in set (0.00 sec)

如果要保留毫秒，则转换为datetime(3) ：

mysql> select cast(trim(trailing 'Z' from '2019-11-28T17:58:12.776Z') as datetime(3));
+-------------------------------------------------------------------------+
| cast(trim(trailing 'Z' from '2019-11-28T17:58:12.776Z') as datetime(3)) |
+-------------------------------------------------------------------------+
| 2019-11-28 17:58:12.776                                                 |
+-------------------------------------------------------------------------+
1 row in set (0.00 sec)