主键和唯一约束有什么区别? [英] What is the difference between a primary key and a unique constraint?

问题描述

有人在面试中问过我这个问题...

Someone asked me this question on an interview...

推荐答案

主键是表上的一个唯一字段，但它的特殊性在于表将该行视为其键.这意味着其他表可以使用此字段来创建与其自身的外键关系.

A primary key is a unique field on a table but it is special in the sense that the table considers that row as its key. This means that other tables can use this field to create foreign key relationships to themselves.

唯一约束仅意味着特定字段必须是唯一的.

A unique constraint simply means that a particular field must be unique.

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