什么时候在MySQL中使用单引号，双引号和反引号 - When to use single quotes, double quotes, and backticks in MySQL

问题：

I am trying to learn the best way to write queries. 我正在尝试学习编写查询的最佳方法。 I also understand the importance of being consistent. 我也了解保持一致的重要性。 Until now, I have randomly used single quotes, double quotes, and backticks without any real thought. 到如今为止，我在没有任何实际考虑的状况下随机使用单引号，双引号和反引号。

Example: 例：

$query = 'INSERT INTO table (id, col1, col2) VALUES (NULL, val1, val2)';

Also, in the above example, consider that table , col1 , val1 , etc. may be variables. 另外，在上面的示例中，请考虑table ， col1 ， val1等能够是变量。

What is the standard for this? 这是什么标准？ What do you do? 你是作什么？

_{I've been reading answers to similar questions on here for about 20 minutes, but it seems like there is no definitive answer to this question. 我已经在这里阅读了大约20分钟的相似问题的答案，可是彷佛没有确切的答案。}

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解决方案：

参考一： https://stackoom.com/question/lVEh/什么时候在MySQL中使用单引号-双引号和反引号
参考二： https://oldbug.net/q/lVEh/When-to-use-single-quotes-double-quotes-and-backticks-in-MySQL