MySQL密钥/唯一密钥

本文介绍了MySQL密钥/唯一密钥的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

Google大多回答有关PRIMARY KEY/UNIQUE KEY差异的问题.但是在MySQL中KEY/UNIQUE KEY呢? MySQL中的KEY是否唯一标识一个元组?

Google mostly answer the question about PRIMARY KEY/UNIQUE KEY difference. But what about KEY/UNIQUE KEY in MySQL? Does`t KEY in MySQL uniquely identify a tuple?

推荐答案

一点也不-带有键的列可以轻松地具有重复的值，该键有助于快速访问它们.唯一键不允许在该列中插入具有现有值的行.

Not at all - a column with a key can easily have duplicate values, the key helps with accessing them fast. A unique key will not allow to insert a row with an already existing value in that column.