查询 3 是 Postgres 9.5 中引入的UPSERT"(= UPDATE 或 INSERT)的 Postgres 语法.

Query 3 is the Postgres syntax for "UPSERT" (= UPDATE or INSERT), introduced in Postgres 9.5.

来自文档:

ON CONFLICT DO UPDATE 保证原子的 INSERT 或 UPDATE 结果；如果没有独立误差，这两个结果之一是保证，即使在高并发下.这也称为 UPSERT –“UPDATE 或 INSERT”.

ON CONFLICT DO UPDATE guarantees an atomic INSERT or UPDATE outcome; provided there is no independent error, one of those two outcomes is guaranteed, even under high concurrency. This is also known as UPSERT – “UPDATE or INSERT”.

这是您要达到的目标的***实践.

This is the best practice for what you are trying to achieve.