哪一个代表空值? undef或空字符串 [英] Which one represents null? undef or empty string

问题描述

我想在表的列中插入null.

哪个代表空值? undef或空字符串''.

Which one represents null? undef or empty string ''.

应该使用哪个?为什么?我知道defined并且可以检查.

Which one should be used and Why? I know about defined and that I can check it.

但是我从数据库的角度看更多.

But I am looking more from perspective of database.

哪个人更恰当地表示null?

更新:我正在使用DBI模块.

推荐答案

DBI使用undef表示SQL NULL.空字符串代表空字符串.

DBI uses undef to represent a SQL NULL. The empty string represents an empty string.

但是，某些数据库不能区分NULL和空字符串. Oracle在这里是一个特别的冒犯者. DBI对此无能为力.

However, some databases don't make a distinction between NULL and the empty string. Oracle is a particular offender here. DBI can't do anything about that.

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