the problem: “Your PHP installation appears to be missing the MySQL extension which is required by WordPress.” is shown when attempting to install wordpress on windows

try this: check your php.ini file and make sure the following line is uncommented (i.e. does not have a semi colon in front of it):

if that is ok, then check for the line in the file that designates the location of the extension_dir. by default mines said:

but i had to change it to the following and then it worked (note: my php installation directory is c:php):

if this occurs on a linux environment, just install php-mysql