如何在SQL Server中将日期从varchar转换为datetime2？

Question

如何将这些日期值从varchar转换为datetime2？

WITH dates AS (
SELECT '6.7.2012' AS dtm
UNION 
SELECT '13.2.2012' AS dtm
UNION
SELECT '3.12.2012' AS dtm
UNION 
SELECT '20.11.2012' AS dtm
)
SELECT CAST(dtm as datetime2) FROM dates
;

这会导致错误:

消息241,级别16,状态1,行6
转换从字符串转换日期和/或时间时失败.

Answer 1

使用try_convert而不是cast:

WITH dates AS (
SELECT '6.7.2012' AS dtm
UNION 
SELECT '13.2.2012' AS dtm
UNION
SELECT '3.12.2012' AS dtm
UNION 
SELECT '20.11.2012' AS dtm
)
SELECT TRY_CONVERT(datetime2, dtm, 104) FROM dates
;

结果:

13.02.2012 00:00:00
20.11.2012 00:00:00
03.12.2012 00:00:00
06.07.2012 00:00:00

注意: try_convert是在2012版本中引入的,对于您需要使用的早期版本convert,如果无法使用指定的样式转换varchar值,则存在异常.