最快检查 PostgreSQL 中是否存在行 [英] Fastest check if row exists in PostgreSQL

问题描述

我有一堆行需要插入到表中，但这些插入总是分批完成的.所以我想检查表中是否存在批处理中的一行，因为这样我就知道它们都被插入了.

I have a bunch of rows that I need to insert into table, but these inserts are always done in batches. So I want to check if a single row from the batch exists in the table because then I know they all were inserted.

所以它不是主键检查，但应该没有太大关系.我想只检查单行，所以 count(*) 可能不好，所以它类似于 exists 我猜.

So its not a primary key check, but shouldn't matter too much. I would like to only check single row so count(*) probably isn't good, so its something like exists I guess.

但由于我对 PostgreSQL 还很陌生，所以我宁愿询问了解的人.

But since I'm fairly new to PostgreSQL I'd rather ask people who know.

我的批次包含具有以下结构的行:

My batch contains rows with following structure:

userid | rightid | remaining_count

因此，如果表中包含任何带有提供的 userid 的行，则意味着它们都存在于那里.

So if table contains any rows with provided userid it means they all are present there.

推荐答案

使用 EXISTS 关键字进行 TRUE/FALSE 返回:

Use the EXISTS key word for TRUE / FALSE return:

select exists(select 1 from contact where id=12)

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