You have to add any other directory to path
set PATH=%PATH%;C:\DirectoryToAdd\ToPath
It doesn't matter if you add %PATH% in the starting or in the end, but you must add it, otherwise your will have your new directory as a path.
Find mySql installation directory ( for example C:\Program Files\MySQL\MySQL Server 5.6\bin) and then you need to type the command above set PATH=%PATH%;C:\Program
Files\MySQL\MySQL Server 5.6\bin
tips:
In command Line Interface use PATH to see what is your path. And you can find more about PATH command.
Your mySql service mightt be turned on to execute commands.
In Windows explorer if you typed cmd.exe in Windows Explorer Address Bar you will be having cmd running from that directory.
If you want to get more insights into SQL, checkout this SQL Course from Intellipaat.