问题描述
有没有比这更好的选择空日期时间字段的方法了?
Is there a better way to select empty datetime fields than this?
SELECT * FROM `table` WHERE `datetime_field` = '0000-00-00 00:00:00'
推荐答案
哪种方式更好?该查询会执行您所要求的所有操作，并且只要在datetime_field上有一个索引，它就会像它将要获得的一样快.
Better in what way? That query does everything you ask of it and, provided there's an index on datetime_field, it's as fast as it's going to get.
如果您担心查询看起来丑陋"，那就不要.其意图很明确.
If you're worried about the query looking "ugly", don't be. Its intent is quite clear.
您可以考虑的唯一可能的改进就是对这些零日期/时间行使用NULL，在这种情况下，查询将变为:
The only possible improvement you could consider is to use NULLs for these zero-date/time rows, in which case your query becomes:
SELECT * FROM `table` WHERE `datetime_field` IS NULL
这就是我要使用符合标准的DBMS的方式.我的理解是，MySQL 可能以这种令人恐惧的方式表示真正的NULL datetime字段，在这种情况下，我想IS NULL可能不起作用.
That's what I'd do with a standards-compliant DBMS. My understanding is that MySQL may represent true NULL datetime fields in this horrific manner, in which case I guess the IS NULL may not work.
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