postgres是否会自动为每一行生成一个ID？ [英] Does postgres automatically generate an id for every row?

问题描述

我一般对Postgres和SQL还是陌生的。我来自NoSQL。更具体的mongodb。在mongodb中，每个文档都有一个由mongodb自动生成的唯一ID。

I am new to postgres and SQL in general. I am coming from NoSQL. More specific mongodb. In mongodb every document had a unique id automatically generated by mongodb.

postgres行会自动具有唯一的ID还是您必须自己生成它们？

Do postgres rows automatically have a unique id or do you have to generate them yourself?

推荐答案

您需要为自己定义一个：

You need to define one for yourself:

create table foo
(
  id integer generated always as identity primary key,
  .... other columns
);

在关系数据库中，您必须自己定义主键，数据库不会对此进行假设。例如通常，用于多对多关系的链接表根本没有生成的PK：

In a relational database you have to define the primary key yourself, the database does not make assumptions about that. e.g. a link table for a many-to-many relationship usually doesn't have a generated PK at all:

create table many_to_many
(
  one_id integer not null references table_one,
  other_id integer not null references other_table,
  primary key (one_id, other_id)
);

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