MySQL:NULL与“" [英] MySQL: NULL vs ""

问题描述

在MySQL的文本字段中使用default null或default ""更好吗?

Is it better to use default null or default "" for text fields in MySQL?

为什么?

更新:我知道每一个的含义.考虑到磁盘空间和性能，我对使用哪种更好的方法很感兴趣.

Update: I know what means each of them. I am interested what is better to use considering disk space and performance.

更新2:嘿，老兄！问题是使用什么更好"而不是每种含义是什么"或如何检查它们" ...

Update 2: Hey ppl! The question was "what is better to use" not "what each means" or "how to check them"...

推荐答案

使用默认的null.在SQL中，null与空字符串(")有很大不同.空字符串特别意味着该值被设置为空. null表示未设置该值或将其设置为null.您会看到不同的含义.

Use default null. In SQL, null is very different from the empty string (""). The empty string specifically means that the value was set to be empty; null means that the value was not set, or was set to null. Different meanings, you see.

不同的含义和不同的用法说明了适当使用它们的重要性.与default ""相比，使用default null可能节省的空间很小，以至于可以忽略不计；但是，按照约定使用正确的默认值的潜在价值是很高的.

The different meanings and their different usages are why it's important to use each of them as appropriate; the amount of space potentially saved by using default null as opposed to default "" is so small that it approaches negligibility; however, the potential value of using the proper defaults as convention dictates is quite high.

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