从字符串字段转换 MySQL 中的日期
我使用的系统将日期存储为 dd/mm/yyyy 格式的字符串.是否可以在 SELECT 查询中将其转换为 yyyy-mm-dd (以便我可以在其上使用 DATE_FORMAT )?MySQL 有日期解析功能吗?
I'm using a system where the dates are stored as strings in the format dd/mm/yyyy. Is it possible to convert this to yyyy-mm-dd in a SELECT query (so that I can use DATE_FORMAT on it)? Does MySQL have a date parsing function?
目前我能想到的唯一方法是连接一堆子字符串，但希望有一个更简单的解决方案.
Currently the only method I can think of is to concatenate a bunch of substrings, but hopefully there's a simpler solution.
(不幸的是，我无法将该字段转换为真正的日期字段，因为它是一个元表:同一列包含不同字段的值，而这些值只是字符串.)
(Unfortunately I can't convert the field to a true date field since it's a meta-table: the same column contains values for different fields that are just strings.)
推荐答案
这个:
STR_TO_DATE(t.datestring, '%d/%m/%Y')
...将字符串转换为日期时间数据类型.为了确保它以您想要的格式出现，请使用 日期格式:
...will convert the string into a datetime datatype. To be sure that it comes out in the format you desire, use DATE_FORMAT:
DATE_FORMAT(STR_TO_DATE(t.datestring, '%d/%m/%Y'), '%Y-%m-%d')
如果你不能改变原始列的数据类型，我建议 创建视图 使用 STR_TO_DATE 调用将字符串转换为 DateTime 数据类型.
If you can't change the datatype on the original column, I suggest creating a view that uses the STR_TO_DATE call to convert the string to a DateTime data type.
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