If you need to specify startup options when you run the server, you can indicate them on the command line or place them in an option file. For options that are used every time the server starts, you may find it most convenient to use an option file to specify your MySQL configuration. This is particularly true under the following circumstances:

When the MySQL server starts on Windows, it looks for option files in several locations, such as the Windows directory, C:\, and the MySQL installation directory (for the full list of locations, see Using Option Files). The Windows directory typically is named something like C:\WINDOWS. You can determine its exact location from the value of the WINDIR environment variable using the following command:

C:\> echo %WINDIR%

MySQL looks for options in each location first in the my.ini file, and then in the my.cnf file. However, to avoid confusion, it is best if you use only one file. If your PC uses a boot loader where C: is not the boot drive, your only option is to use the my.ini file. Whichever option file you use, it must be a plain text file.

You can also make use of the example option files included with your MySQL distribution; see Preconfigured Option Files.

An option file can be created and modified with any text editor, such as Notepad. For example, if MySQL is installed in E:\mysql and the data directory is in E:\mydata\data, you can create an option file containing a [mysqld] section to specify values for the basedir and datadir options:

[mysqld]
# set basedir to your installation path
basedir=E:/mysql
# set datadir to the location of your data directory
datadir=E:/mydata/data

Note that Windows path names are specified in option files using (forward) slashes rather than backslashes. If you do use backslashes, double them:

[mysqld]
# set basedir to your installation path
basedir=E:\\mysql
# set datadir to the location of your data directory
datadir=E:\\mydata\\data

The rules for use of backslash in option file values are given in Using Option Files.

MySQL Enterprise.  For expert advice on the start-up options appropriate to your circumstances, subscribe to the MySQL Enterprise Monitor. For more information, see http://www.mysql.com/products/enterprise/advisors.html.

In MySQL 5.1.23 and earlier, the MySQL installer places the data directory directly under the directory where you install MySQL. On MySQL 5.1.24 and later, the data directory is located within the AppData directory for the user running MySQL.

If you would like to use a data directory in a different location, you should copy the entire contents of the data directory to the new location. For example, if you want to use E:\mydata as the data directory instead, you must do two things: