插入行仅如果行不存在 [英] Insert a Row Only if a Row does not Exist

问题描述

我建立一个计数器。我有一篇文章目录和跟踪访问者。当访问者来到我插入文章ID并在数据库中的IP地址。首先，我检查，看看是否存在知识产权的文章编号，如果IP不存在我做的插入。这是两个查询 - 有没有办法让这个一个查询

I am building a hit counter. I have an article directory and tracking unique visitors. When a visitor comes i insert the article id and their IP address in the database. First I check to see if the ip exists for the article id, if the ip does not exist I make the insert. This is two queries -- is there a way to make this one query

另外，我不使用我经常使用内联SQL存储过程

Also, I am not using stored procedures I am using regular inline sql

推荐答案

这里有一些选择：

 INSERT IGNORE INTO `yourTable`
  SET `yourField` = 'yourValue',
  `yourOtherField` = 'yourOtherValue';

这是MySQL参考手册：如果你使用ignore关键字，在执行INSERT语句中出现的错误作为警告处理来代替。例如，如果没有理睬，说复制表中现有的唯一索引或主键值的行时，会导致重复键错误和声明被中止。）如果记录不存在，它会创建

from MySQL reference manual: "If you use the IGNORE keyword, errors that occur while executing the INSERT statement are treated as warnings instead. For example, without IGNORE, a row that duplicates an existing UNIQUE index or PRIMARY KEY value in the table causes a duplicate-key error and the statement is aborted.".) If the record doesn't yet exist, it will be created.

另一种选择是：

INSERT INTO yourTable (yourfield,yourOtherField) VALUES ('yourValue','yourOtherValue')
ON DUPLICATE KEY UPDATE yourField = yourField;

不会引发错误或警告。

Doesn't throw error or warning.

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