MySQL转储文件和注释掉的行

I have these lines at the top of a MySQL .sql file (dumped with phpMyAdmin):

我将这些行放在MySQL .sql文件的顶部（使用phpMyAdmin转储）：

/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8 */;

But they all seem to be commented out. So will MySQL ignore them when the file is loaded back into a database? If so, why generate these lines at all?

但他们似乎都被评论出来了。那么，当文件被加载回数据库时，MySQL会忽略它们吗？如果是这样，为什么要产生这些线？

2 个解决方案

#1

These are conditional comments aimed at certain versions of mySQL.

这些是针对某些版本的mySQL的条件评论。

From here and here:

从这里到这里：

MySQL version specific comments start with /*!
MySQL版本的具体注释以/ *开头！
And end with */
以* /结束
Version numbers are always 5 digits
版本号始终为5位数
Version numbers are in the format major release number, minor release number, revision number with the major being 1 digit and the minor and revision being 2 digits left-padded with 0’s
版本号的格式为主要版本号，次要版本号，版本号，主要版本为1位，次要版本为2位数，左侧填充0位
Version specific comments will target any version equal to or higher than the version number listed
特定于版本的注释将针对等于或高于列出的版本号的任何版本

#2

MySQL will parse and execute these lines of code, I believe for localization and character-encoding stuff, because the comments start with /*! (with the exclamation mark) instead of just the C-style /*.

MySQL将解析并执行这些代码行，我相信本地化和字符编码的东西，因为注释以/ *开头！（带感叹号）而不仅仅是C风格/ *。

Think of it the same way you do conditional comments and Internet Explorer.  looks like any plain old HTML comment to other browsers, but IE recognizes this special comment and parses it as needed. Likewise, /*! */ looks like any other comment to other SQL DBMSes but is special to MySQL.

可以像使用条件注释和Internet Explorer一样考虑它。 <！ - [if IE]> <！[endif] - >看起来像是对其他浏览器的任何普通的旧HTML评论，但IE会识别此特殊注释并根据需要对其进行解析。同样，/ *！ * /看起来像对其他SQL DBMS的任何其他注释，但对MySQL来说是特殊的。

#1