PostgreSQL 如果外键存在则插入 [英] PostgreSQL insert if foreign key exists

问题描述

仅当外键(在本例中为模型)存在时，如何才能在带有外键引用的表中插入新行?

How can I insert a new row in a table with a foreign key reference only if the foreign key (in this case model) exists?

目前我有以下声明:

INSERT INTO furniture (model, type) VALUES (modelA, chair)

推荐答案

如果 FK 不存在，请使用不返回任何内容的 SELECT.

Use a SELECT that returns nothing if the FK does not exist.

INSERT INTO furniture (model, type) 
select 'modelA', 'chair'
where exists (select * 
              from model 
              where model.model = 'modelA');

你没有告诉我们引用的表叫什么.我假设它是 model - 您需要将其调整为真实姓名.

You did not tell us what the referenced table is called. I assumed it's model - you need to adjust that to the real names.

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