MySQL自动将字符串转换为where子句中的整数? [英] MySQL automatic string to integer casting in where clause?

问题描述

我对MySQL并不陌生，但是今天巧合的是，我的代码中发生了一种奇怪的情况，这使我感到惊讶.有人可以解释为什么这会给我相同的结果吗?

I am not new to MySQL but a strange situation happened in my code today coincidently which got me surprised. Can someone explain why this gives me identical results?

SELECT * FROM `products` WHERE id = 12

和

SELECT * FROM `products` WHERE id = '12ABC'

在两种情况下，我得到的结果都是相同的，并且选择了相同的记录.我希望第二个人不会给我任何回报?我的ID字段是int(11)，未签名，并且auto_increment标志处于打开状态.

In both cases I get the same result with the same record being selected. I would expect that second one would return me nothing?! My ID field is int(11) unsigned with auto_increment flag turned on.

推荐答案

来自MySQL文档:

当运算符与不同类型的操作数一起使用时，会发生类型转换以使操作数兼容

When an operator is used with operands of different types, type conversion occurs to make the operands compatible

文档

因此，基本上，'12ABC'被强制转换为12.

So basically, '12ABC' is cast to 12.

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