所有数据库表都应该有主键吗？ [英] Should all database tables have a primary key?

问题描述

是否是给每个数据库表一个主键的好习惯？在我看来，如果主键不是明确需要，那么它只是在我的数据库中更多的杂乱。

Is it good practice to give every database table a primary key? It seems to me that if the primary key is not explicitly needed, then it would just be extra clutter in my database.

推荐答案

在OLTP数据库您几乎总是（在我的情况下总是）有某种主键。有时候，Guid，有时是自动编号/身份字段，有时由应用程序或客户设置。有时甚至是多个字段的组合。这是因为你通常希望唯一标识，从表中的任何给定行。

When you probably WOULD:

In an OLTP database you'd almost always (in my case always) have a primary key of some sort. Sometimes Guid, sometimes autonumber/identity fields, sometimes set by the application or the customer. Sometimes even a combination of more than one field. This is because you'll typically want to uniquely identify any given row from the table.

此外，主键是由查询优化应该提高性能使用限制对于查找并加入

Also, a primary key is a constraint used by the query optimiser that should improve performance for lookups and joins.

唯一的一次，你就不必主键位于报告表中，可能位于非规范数据仓库中。

The only time you wouldn't have a primary key is in a "reporting" table, probably in a denormalised data warehouse.

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