替换为查询语法 [英] Replace Into Query Syntax

问题描述

我想使用replace into语句更新相同模式的表。最后，我需要能够更新可能已更改的值的大表。

I want to be able to update a table of the same schema using a "replace into" statement. In the end, I need to be able to update a large table with values that may have changed.

这是我开始使用的查询：

Here is the query I am using to start off:

REPLACE INTO table_name
(visual, inspection_status, inspector_name, gelpak_name, gelpak_location),
VALUES (3, 'Partially Inspected', 'Me', 'GP1234', 'A01');

我不明白是数据库引擎如何知道什么是重复行，什么是't？这个数据是非常重要的，我不能冒着数据被损坏的风险。是简单的如果列出的所有列都有相同的值，它是一个重复的行？

What I don't understand is how does the database engine know what is a duplicate row and what isn't? This data is extremely important and I can't risk the data being corrupted. Is it as simple as "if all columns listed have the same value, it is a duplicate row"?

我只是想弄清楚一个有效的方法因此我可以在一分钟内更新> 45,000行。

I am just trying to figure out an efficient way of doing this so I can update > 45,000 rows in under a minute.

推荐答案

像文档说：

REPLACE的工作原理INSERT，除了如果表中的旧行与PRIMARY KEY或UNIQUE索引的新行具有相同的值，则在插入新行之前删除旧行。

REPLACE works exactly like INSERT, except that if an old row in the table has the same value as a new row for a PRIMARY KEY or a UNIQUE index, the old row is deleted before the new row is inserted.

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